test: lint PRs on synchronize events

Since synchronize events clears the status checks, it needs to be re-run.

Author: Sam Harrison

.github/workflows/pr-lint.yml

@@ -1,7 +1,7 @@
 name: Lint PR
 on:
   pull_request_target:
-    types: [ opened, edited, reopened ]
+    types: [ opened, edited, synchronize, reopened ]
 
 jobs:
   validate: