Get CI running again on main.

Author: hameerabbasi

.github/workflows/ci.yml

@@ -3,7 +3,7 @@ defaults:
     shell: bash -leo pipefail {0}
 
 concurrency:
-  group: ${{ github.head_ref }}
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
   cancel-in-progress: true
 
 jobs: