Also check PR title, to fully replace the bot

.github/workflows/check-labels.yaml → .github/workflows/check-title-and-labels.yaml

@@ -1,17 +1,27 @@
 # based on https://stackoverflow.com/a/75036059 and
 # https://github.com/astropy/astropy/blob/main/.github/workflows/check_milestone.yml
-name: Check PR labels
+name: Check PR title and labels
 
 on:
   # So it cannot be skipped.
   pull_request_target:
-    types: [opened, synchronize, labeled, unlabeled]
+    types: [opened, edited, synchronize, labeled, unlabeled]
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.head_ref }}
   cancel-in-progress: true
 
 jobs:
+  check-title:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/github-script@v7
+        with:
+          script: |
+            if (/^\[?WIP\b/i.test(context.payload.pull_request.title)) {
+              core.setFailed("WIP pull requests can't be merged.");
+            }
+
   check-labels:
     runs-on: ubuntu-latest
     steps: