Add release branches to the pull request checks (#467)

Author: cmcgee1024

.github/workflows/pull_request.yml

@@ -4,7 +4,7 @@ on:
   pull_request:
     types: [opened, reopened, synchronize]
   push:
-    branches: [main]
+    branches: [main, 'release/*']
 
 jobs:
   soundness: