Codechange: add automation for (re)setting the 'work: needs rebase' label on PRs

.github/workflows/rebase-checker.yml

@@ -0,0 +1,19 @@
+name: "Update 'work: needs rebase' label status"
+on:
+  # So that PRs touching the same files as the push are updated
+  push:
+  # So that the `dirtyLabel` is removed if conflicts are resolve
+  # We recommend `pull_request_target` so that github secrets are available.
+  # In `pull_request` we wouldn't be able to change labels of fork PRs
+  pull_request_target:
+    types: [synchronize]
+
+jobs:
+  main:
+    runs-on: ubuntu-latest
+    steps:
+      - name: check if prs are in need of a rebase
+        uses: eps1lon/actions-label-merge-conflict@v3
+        with:
+          dirtyLabel: "work: needs rebase"
+          repoToken: "${{ secrets.GITHUB_TOKEN }}"