fix(ci): skip integration tests for fork PRs

Fork PRs do not have access to repository secrets. The integration-tests
job calls JSON.parse(process.env.INTEGRATION_CERTS) which crashes with
an empty string, causing 24 out of 30 jobs to fail immediately.

Skip the entire integration-tests job for fork PRs by checking that the
head repo matches the base repo, using the same pattern already used in
the check-permissions job.

Author: jacekradko

.github/workflows/ci.yml

@@ -274,7 +274,9 @@ jobs:
 
   integration-tests:
     needs: [check-permissions, build-packages]
-    if: ${{ github.event_name != 'pull_request' || github.event.pull_request.draft == false }}
+    if: >-
+      ${{ (github.event_name != 'pull_request' || github.event.pull_request.draft == false)
+      && (github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name == github.repository) }}
     name: Integration Tests (${{ matrix.test-name }}, ${{ matrix.test-project }}${{ matrix.next-version && format(', {0}', matrix.next-version) || '' }})
     permissions:
       contents: read