Fix test workflow condition to run on pull requests

Author: mu373

.github/workflows/test.yml

@@ -27,7 +27,7 @@ jobs:
   test:
     name: Test
     runs-on: ubuntu-latest
-    if: ${{ github.event.head_commit && !contains(github.event.head_commit.message, '[skip ci]') }}
+    if: ${{ !contains(github.event_name == 'pull_request' && github.event.pull_request.title || github.event.head_commit.message || '', '[skip ci]') }}
 
     steps:
       - name: Checkout repository