Refactor GitHub workflow files for improved concurrency handling

This commit refactors the GitHub workflow files to improve concurrency handling. The changes include adding a new `concurrency` section to each file, which allows builds to complete even if merging happens faster. This makes it easier to discover at which point something broke. The `group` value in the `concurrency` section is set based on the branch being built, using a combination of the branch name and the commit SHA.

The affected files are:
- `.github/workflows/clang-format-check.yml`
- `.github/workflows/codecov-upload.yml`
- `.github/workflows/codeql-analysis.yml`
- `.github/workflows/linux-clang-pkgx.yml`
- `.github/workflows/linux-clang.yml`
- `.github/workflows/linux-gcc.yml`
- `.github/workflows/macos.yml`
- `.github/workflows/sonarcloud.yml`
- `.github/workflows/windows-msvc.yml`
- `.github/workflows/windows-pkgx.yml`

Additionally, the Travis CI configuration file (`.travis.yml`) has been updated to handle different versions of GCC and Clang compilers.

These changes aim to enhance build performance and reliability by ensuring that all builds complete successfully, regardless of merge speed.

.github/workflows/clang-format-check.yml

@@ -1,5 +1,10 @@
 name: clang-format Check
 on: [push, pull_request]
+
+concurrency:
+  # Documentation suggests ${{ github.head_ref }}, but that's only available on pull_request/pull_request_target triggers, so using ${{ github.ref }}.
+  # On master, we want all builds to complete even if merging happens faster to make it easier to discover at which point something broke.
+  group: ${{ github.ref == 'refs/heads/master' && format('ci-master-{0}', github.sha) || format('ci-{0}', github.ref) }}
 jobs:
   formatting-check:
     name: Formatting Check

.github/workflows/codecov-upload.yml

@@ -2,6 +2,11 @@ name: CodeCov
 
 on: [push, pull_request, workflow_dispatch]
 
+concurrency:
+  # Documentation suggests ${{ github.head_ref }}, but that's only available on pull_request/pull_request_target triggers, so using ${{ github.ref }}.
+  # On master, we want all builds to complete even if merging happens faster to make it easier to discover at which point something broke.
+  group: ${{ github.ref == 'refs/heads/master' && format('ci-master-{0}', github.sha) || format('ci-{0}', github.ref) }}
+
 jobs:
   codecov:
     name: CodeCov

.github/workflows/codeql-analysis.yml

@@ -21,6 +21,11 @@ on:
     - cron: '26 7 * * 0'
   workflow_dispatch:
 
+concurrency:
+  # Documentation suggests ${{ github.head_ref }}, but that's only available on pull_request/pull_request_target triggers, so using ${{ github.ref }}.
+  # On master, we want all builds to complete even if merging happens faster to make it easier to discover at which point something broke.
+  group: ${{ github.ref == 'refs/heads/master' && format('ci-master-{0}', github.sha) || format('ci-{0}', github.ref) }}
+
 jobs:
   analyze:
     name: Analyze

.github/workflows/linux-clang-pkgx.yml

@@ -2,6 +2,11 @@ name: Linux Clang with pkgx
 
 on: [push, pull_request, workflow_dispatch]
 
+concurrency:
+  # Documentation suggests ${{ github.head_ref }}, but that's only available on pull_request/pull_request_target triggers, so using ${{ github.ref }}.
+  # On master, we want all builds to complete even if merging happens faster to make it easier to discover at which point something broke.
+  group: ${{ github.ref == 'refs/heads/master' && format('ci-master-{0}', github.sha) || format('ci-{0}', github.ref) }}
+
 jobs:
   build:
     runs-on: ubuntu-latest

.github/workflows/linux-clang.yml

@@ -2,6 +2,11 @@ name: Linux Clang
 
 on: [push, pull_request, workflow_dispatch]
 
+concurrency:
+  # Documentation suggests ${{ github.head_ref }}, but that's only available on pull_request/pull_request_target triggers, so using ${{ github.ref }}.
+  # On master, we want all builds to complete even if merging happens faster to make it easier to discover at which point something broke.
+  group: ${{ github.ref == 'refs/heads/master' && format('ci-master-{0}', github.sha) || format('ci-{0}', github.ref) }}
+
 jobs:
   build:
     runs-on: ubuntu-latest

.github/workflows/linux-gcc.yml

@@ -2,6 +2,11 @@ name: Linux GCC
 
 on: [push, pull_request, workflow_dispatch]
 
+concurrency:
+  # Documentation suggests ${{ github.head_ref }}, but that's only available on pull_request/pull_request_target triggers, so using ${{ github.ref }}.
+  # On master, we want all builds to complete even if merging happens faster to make it easier to discover at which point something broke.
+  group: ${{ github.ref == 'refs/heads/master' && format('ci-master-{0}', github.sha) || format('ci-{0}', github.ref) }}
+
 jobs:
   build:
     runs-on: ubuntu-latest

.github/workflows/macos.yml

@@ -2,6 +2,11 @@ name: macOS
 
 on: [push, pull_request, workflow_dispatch]
 
+concurrency:
+  # Documentation suggests ${{ github.head_ref }}, but that's only available on pull_request/pull_request_target triggers, so using ${{ github.ref }}.
+  # On master, we want all builds to complete even if merging happens faster to make it easier to discover at which point something broke.
+  group: ${{ github.ref == 'refs/heads/master' && format('ci-master-{0}', github.sha) || format('ci-{0}', github.ref) }}
+
 jobs:
   build:
     runs-on: macos-13

.github/workflows/sonarcloud.yml

@@ -2,6 +2,11 @@ name: SonarCloud
 
 on: [push, pull_request, workflow_dispatch]
 
+concurrency:
+  # Documentation suggests ${{ github.head_ref }}, but that's only available on pull_request/pull_request_target triggers, so using ${{ github.ref }}.
+  # On master, we want all builds to complete even if merging happens faster to make it easier to discover at which point something broke.
+  group: ${{ github.ref == 'refs/heads/master' && format('ci-master-{0}', github.sha) || format('ci-{0}', github.ref) }}
+
 jobs:
   sonarcloud:
     name: SonarCloud

.github/workflows/windows-msvc.yml

@@ -2,6 +2,11 @@ name: Windows
 
 on: [workflow_dispatch]
 
+concurrency:
+  # Documentation suggests ${{ github.head_ref }}, but that's only available on pull_request/pull_request_target triggers, so using ${{ github.ref }}.
+  # On master, we want all builds to complete even if merging happens faster to make it easier to discover at which point something broke.
+  group: ${{ github.ref == 'refs/heads/master' && format('ci-master-{0}', github.sha) || format('ci-{0}', github.ref) }}
+
 jobs:
   build:
     runs-on: windows-latest

.github/workflows/windows-pkgx.yml

@@ -2,6 +2,11 @@ name: Windows pkgx
 
 on: [workflow_dispatch]
 
+concurrency:
+  # Documentation suggests ${{ github.head_ref }}, but that's only available on pull_request/pull_request_target triggers, so using ${{ github.ref }}.
+  # On master, we want all builds to complete even if merging happens faster to make it easier to discover at which point something broke.
+  group: ${{ github.ref == 'refs/heads/master' && format('ci-master-{0}', github.sha) || format('ci-{0}', github.ref) }}
+
 jobs:
   build:
     runs-on: windows-latest

.travis.yml

@@ -133,10 +133,12 @@ before_install:
   - sudo install -m 755 pkgx /usr/local/bin
   - pkgx --help
   - if [[ "$CXX" == "g++" ]]; then
+    |
       env +gcc@13
       export CXX="g++-13" CC="gcc-13"
     fi
   - if [[ "$CXX" == "clang++" ]]; then
+    |
       env +clang@16
       export CXX="clang++-16" CC="clang-16"
     fi