setup upstream workflow

.github/workflows/upstream-check.yml

@@ -0,0 +1,48 @@
+name: Upstream
+
+on:
+  pull_request:
+    types: [ opened, synchronize, reopened, ready_for_review ]
+
+jobs:
+  upstream_run:
+    name: ${{ matrix.repo }} (dry-run)
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+
+    concurrency:
+      group: upstream-check-${{github.event_name}}-${{ matrix.repo }}-${{ github.head_ref || github.run_id }}
+      cancel-in-progress: true
+
+    strategy:
+      fail-fast: false
+      matrix:
+        repo:
+          - 'redaxo/redaxo'
+          - 'yakamara/yform'
+          - 'yakamara/redaxo_yrewrite'
+          - 'yakamara/ycom'
+
+    if: github.event.pull_request.draft == false
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          repository: ${{ matrix.repo }}
+
+      - name: Setup PHP
+        id: setup-php
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: 8.1
+          coverage: none
+
+      - name: set redaxo/php-cs-fixer-config to current branch
+        run: composer require redaxo/php-cs-fixer-config:dev-${{ github.head_ref }} --no-scripts --no-update
+
+      - uses: "ramsey/composer-install@v2"
+        with:
+          dependency-versions: "highest" # to trigger "composer update" instead of "composer install" but limited to redaxo/php-cs-fixer-config updates only
+          composer-options: "redaxo/php-cs-fixer-config --prefer-dist --no-progress --with-all-dependencies"
+
+      - name: run php-cs-fixer (dry-run)
+        run: php-cs-fixer fix -v --ansi --dry-run