Fix code style workflow for fork pull requests

Author: yankewei

.github/workflows/php-cs-fixer.yml

@@ -22,7 +22,15 @@ jobs:
   lint:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v6
+      - name: Checkout branch
+        if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name == github.repository
+        uses: actions/checkout@v6
+        with:
+          ref: ${{ github.head_ref || github.ref_name }}
+
+      - name: Checkout pull request merge ref
+        if: github.event_name == 'pull_request' && github.event.pull_request.head.repo.full_name != github.repository
+        uses: actions/checkout@v6
 
       - name: Setup PHP
         uses: shivammathur/setup-php@v2
@@ -34,9 +42,15 @@ jobs:
           composer install -q --no-ansi --no-interaction --no-scripts --no-progress --prefer-dist
 
       - name: Run PHP CS Fixer
+        if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name == github.repository
         run: ./vendor/bin/php-cs-fixer fix --allow-risky=yes
 
+      - name: Check PHP CS Fixer
+        if: github.event_name == 'pull_request' && github.event.pull_request.head.repo.full_name != github.repository
+        run: ./vendor/bin/php-cs-fixer fix --allow-risky=yes --dry-run --diff
+
       - name: Commit Changes
+        if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name == github.repository
         uses: stefanzweifel/git-auto-commit-action@v5
         with:
           commit_message: 🪄 Code Style Fixes