ci: subscribe to edited PR events so workflows re-fire after Graphite restacks (#429)

## What

Brief description of the change.

## Why

Why is this change needed?

## How

How was this implemented? Any notable design decisions?

## Test plan

How was this tested?

- [ ] Unit tests added/updated
- [ ] Manual testing performed
- [ ] Documentation updated (if applicable)

.github/workflows/ci.yml

@@ -2,6 +2,12 @@ name: CI
 
 on:
   pull_request:
+    # `edited` is required so the workflow re-fires when a PR's base ref is
+    # set back to `main` after a Graphite stack restack momentarily flips
+    # the base off of `main`. Without it, `pull_request` triggers are not
+    # re-evaluated on `base_ref_changed`, leaving required checks skipped
+    # for that head SHA forever.
+    types: [opened, synchronize, reopened, edited]
     branches: [main]
   push:
     branches: [main]

.github/workflows/windows-render.yml

@@ -8,6 +8,12 @@ name: Windows render verification
 
 on:
   pull_request:
+    # `edited` is required so the workflow re-fires when a PR's base ref is
+    # set back to `main` after a Graphite stack restack momentarily flips
+    # the base off of `main`. Without it, `pull_request` triggers are not
+    # re-evaluated on `base_ref_changed`, leaving required checks skipped
+    # for that head SHA forever.
+    types: [opened, synchronize, reopened, edited]
     branches: [main]
   push:
     branches: [main]