Update fix-php-code-style-issues.yml (#573)

Author: PeteBishwhip

.github/workflows/fix-php-code-style-issues.yml

@@ -22,7 +22,7 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@v4
         with:
-          ref: ${{ github.head_ref }}
+          ref: ${{ github.head_ref || github.sha }}
 
       - name: Check PHP code style issues
         if: github.event_name == 'push'