Bump actions/checkout from 1 to 4

Bumps [actions/checkout](https://github.com/actions/checkout) from 1 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v1...v4)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/CI.yml

@@ -26,7 +26,7 @@ jobs:
           - x64
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
       - name: Julia Setup
         uses: julia-actions/setup-julia@v2
         with:

.github/workflows/docs-cleanup.yml

@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout gh-pages branch
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
         with:
           ref: gh-pages
       - name: Delete preview and history + push changes

.github/workflows/documenter.yml

@@ -18,7 +18,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
       - name: Setup Julia
         uses: julia-actions/setup-julia@v2
       - name: Cache

.github/workflows/style.yml

@@ -23,7 +23,7 @@ jobs:
       - uses: julia-actions/setup-julia@latest
         with:
           version: ${{ matrix.julia-version }}
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v4
       - name: Instantiate `format` environment and format
         run: |
           julia --project=format -e 'using Pkg; Pkg.instantiate()'