make test workflow work on forks

Author: aarsilv

.github/workflows/run-tests.yml

@@ -39,17 +39,17 @@ jobs:
         echo "Test Data: sdk-test-data@${TEST_DATA_BRANCH_NAME}"
         echo "SDK Branch: php-sdk@${SDK_BRANCH_NAME}"
 
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v5
       with:
-        repository: Eppo-exp/php-sdk
-        ref: ${{ env.SDK_BRANCH_NAME}}
+        repository: ${{ github.event.pull_request.head.repo.full_name || 'Eppo-exp/php-sdk' }}
+        ref: ${{ env.SDK_BRANCH_NAME }}
 
     - name: Validate composer.json and composer.lock
       run: composer validate --strict
 
     - name: Cache Composer packages
       id: composer-cache
-      uses: actions/cache@v3
+      uses: actions/cache@v4
       with:
         path: vendor
         key: ${{ runner.os }}-php-${{ hashFiles('**/composer.lock') }}