Configure the concurrency to abort any preceding GHA runs in progress

.github/workflows/ci.yml

@@ -4,6 +4,10 @@ on:
   push:
   pull_request:
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
 jobs:
   run-tests:
     name: ${{ matrix.os }} ruby-${{ matrix.ruby }} ${{ matrix.database_adapter }}