Do not run CI in PR twice (#2082)

Author: dudoslav

.github/workflows/ci.yml

@@ -1,6 +1,11 @@
 name: TileDB Python CI
 
-on: [push, pull_request, workflow_dispatch]
+on: 
+  push:
+    branches: [dev]
+  pull_request:
+    branches: [dev]
+  workflow_dispatch:
 
 concurrency:
   group: ${{ github.head_ref || github.run_id }}