Fix: Add 'synchronize' event to PR workflow triggers

The workflow was missing 'synchronize' trigger type, causing it to not
run when PRs are updated with new commits. This is needed to run CI
on PR updates (e.g., after rebasing or pushing new commits).

Trigger types now:
- opened: New PR created
- reopened: Closed PR reopened
- synchronize: PR updated with new commits

Author: jensens

.github/workflows/tests.yaml

@@ -8,6 +8,7 @@ on:
     types:
       - "reopened"
       - "opened"
+      - "synchronize"
   workflow_call:
   workflow_dispatch: