ci: add combine PRs workflow

See https://github.com/github/combine-prs

Author: coderbyheart

.github/workflows/combine-prs.yaml

@@ -0,0 +1,22 @@
+name: Combine PRs
+
+on:
+  schedule:
+    - cron: "0 3 * * *"
+  workflow_dispatch:
+
+permissions:
+  contents: write
+  pull-requests: write
+  checks: read
+
+jobs:
+  combine-prs:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: combine-prs
+        id: combine-prs
+        uses: github/[email protected]
+        with:
+          branch_prefix: renovate