Run github actions on main (#7292)

We want the nice looking green checkmark on our main branch too.

This PR includes running on pushes to release branches too, but that
won't come into effect until we have release branches with this
workflow file.

.github/workflows/build_and_test.yml

@@ -10,6 +10,10 @@ on:
         required: false
         default: false
         type: boolean
+  push:
+    branches:
+      - "main"
+      - "release-*"
   pull_request:
     types: [opened, reopened,synchronize]
 jobs: