Cancel primer for old commits on PRs (#13846)

Author: hauntsaninja

.github/workflows/mypy_primer.yml

@@ -15,6 +15,10 @@ on:
     - 'mypy/test/**'
     - 'test-data/**'
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
 jobs:
   mypy_primer:
     name: Run mypy_primer

.github/workflows/mypy_primer_comment.yml

@@ -15,6 +15,7 @@ jobs:
   comment:
     name: Comment PR from mypy_primer
     runs-on: ubuntu-latest
+    if: ${{ github.event.workflow_run.conclusion == 'success' }}
     steps:
       - name: Download diffs
         uses: actions/github-script@v6