ci: cancel PR actions on new commits

Author: Firestar99

.github/workflows/push.yaml

@@ -7,6 +7,11 @@ on:
   pull_request:
   workflow_dispatch:
 
+# Cancel PR actions on new commits
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref || github.run_id }}
+  cancel-in-progress: true
+
 env:
   # For setup-rust, see https://github.com/moonrepo/setup-rust/issues/22
   GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}