ci: add auto reviewer (#990)

.github/workflows/pr-auto.yml

@@ -0,0 +1,18 @@
+name: auto-pr
+
+on:
+  pull_request_target:
+    types:
+      - opened
+
+jobs:
+  review:
+    if: github.event.action == 'opened' && !endsWith(github.event.pull_request.user.login, '[bot]')
+    runs-on: ubuntu-24.04
+    permissions:
+      pull-requests: write
+    steps:
+      - uses: hkusu/review-assign-action@5bee595fdb9765d4a0bd35724b6302fa15569158 # v1.4.0
+        with:
+          reviewers: ${{ vars.REVIEWERS }}
+          max-num-of-reviewers: 2