Merge conflict labeller (#31)

.github/workflows/label-merge-conflicts.yml

@@ -0,0 +1,26 @@
+name: "Merge Conflicts"
+on:
+    # So that PRs touching the same files as the push are updated
+    push:
+        branches: [beta]
+    # 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
+        permissions:
+            contents: read
+            pull-requests: write
+        steps:
+            - name: Check PRs for conflicts
+              uses: eps1lon/actions-label-merge-conflict@v3
+              with:
+                  dirtyLabel: "merge conflicts"
+                  # removeOnDirtyLabel: "PR: ready to ship"
+                  repoToken: "${{ secrets.GITHUB_TOKEN }}"
+                  commentOnDirty: "This pull request has conflicts, please resolve those before we can evaluate the pull request."
+                  commentOnClean: "Conflicts have been resolved. A maintainer will review the pull request shortly."