chore: enable more triggers for the CI checks

This is mostly experimental; I'm hoping to be able to trigger checks
on some existing PRs...

.github/workflows/build_and_test.yml

@@ -2,6 +2,7 @@ name: Build and Test
 
 on:
   pull_request:
+    types: [opened, reopened, synchronize, ready_for_review, review_requested]
     branches-ignore:
       - 'gh-pages'
   push: