Update pipeline triggers

Author: jnonino

.github/workflows/pipeline-example-multiple-containers.yml

@@ -1,8 +1,11 @@
 name: Terraform
 on:
   push:
+    branches:
+      - 'main'
   pull_request:
-    types: [opened, reopened]
+    branches:
+      - 'main'
 
 jobs:
   check-format: