[CI] Improve CI (#5078)

Raname workflow to be clear.

- vLLM version: v0.12.0
- vLLM main:
ad32e3e19c

Signed-off-by: wangxiyuan <wangxiyuan1007@gmail.com>

.github/workflows/bot_merge_conflict.yaml

@@ -0,0 +1,20 @@
+name: Merge Conflict Labeler
+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 dirty
+        uses: eps1lon/actions-label-merge-conflict@v3
+        with:
+          dirtyLabel: "merge-conflicts"
+          repoToken: "${{ secrets.GITHUB_TOKEN }}"
+          commentOnDirty: "This pull request has conflicts, please resolve those before we can evaluate the pull request."