ci(pr-title): Add synchronize to pull request event types trigger

Without synchronize the Required Status Check does not run, which can
block merging.

.github/workflows/pr-title.yaml

@@ -1,7 +1,7 @@
 name: Validate PR title
 on:
   pull_request:
-    types: [opened, edited]
+    types: [opened, edited, synchronize]
 
 # Disable permissions for all available scopes
 permissions: {}