ci: only run molecule matrix on pull_request, not every push

refs mrlesmithjr/cookiecutter-ansible-role#74

Author: mrlesmithjr

.github/workflows/default.yml

@@ -1,9 +1,5 @@
 name: Verification
 on:
-  push:
-    branches-ignore:
-      - main
-      - master
   pull_request:
     branches:
       - develop