Auto-cancel workflows when pushing to a branch

Author: nedbat

.github/workflows/cancel.yml

@@ -0,0 +1,20 @@
+# Licensed under the Apache License: http://www.apache.org/licenses/LICENSE-2.0
+# For details: https://github.com/nedbat/coveragepy/blob/master/NOTICE.txt
+
+# This action finds in-progress Action jobs for the same branch, and cancels
+# them. There's little point in continuing to run superceded jobs.
+
+name: Cancel
+
+on:
+  push:
+
+jobs:
+  cancel:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Cancel Previous Runs
+        uses: styfle/[email protected]
+        with:
+          access_token: ${{ github.token }}
+          workflow_id: coverage.yml, kit.yml, quality.yml, testsuite.yml