ci: fix linter and tests workflows for PRs

Author: SlimDeluxe

.github/workflows/linter.yml

@@ -22,7 +22,7 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@v4
         with:
-          ref: ${{ github.head_ref }}
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
 
       - name: Run Laravel Pint
         uses: aglipanci/laravel-pint-action@latest

.github/workflows/test-runner.yml

@@ -41,7 +41,7 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@v4
         with:
-          ref: ${{ github.head_ref }}
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
 
       - name: Validate composer.json and composer.lock
         run: composer validate --strict