Update ci.yaml

We missed test coverage for the new 2.x branch

Author: alexeagle

.github/workflows/ci.yaml

@@ -4,9 +4,9 @@ name: CI
 on:
     # Triggers the workflow on push or pull request events but only for the main branch
     push:
-        branches: [main]
+        branches: [main, 2.x]
     pull_request:
-        branches: [main]
+        branches: [main, 2.x]
 
     # Allows you to run this workflow manually from the Actions tab
     workflow_dispatch: