Updated validate-submodule CI to use branch filter (#239)

Author: amit-momin

.github/workflows/validate-submodule.yml

@@ -3,13 +3,14 @@ permissions: {}
 
 on:
   pull_request:
-    types: [opened, synchronize, reopened]
+    branches:
+      - capabilities-development
   push:
-    branches: [capabilities-development]
+    branches:
+      - capabilities-development
 
 jobs:
   validate-submodule:
-    if: github.event_name == 'push' || github.base_ref == 'capabilities-development'
     permissions:
       contents: read
     runs-on: ubuntu-latest