add action for syncing to gitee

.github/workflows/mirror.yml

@@ -0,0 +1,17 @@
+name: Mirroring
+
+on: [push, delete]
+
+jobs:
+  to_gitee:
+    runs-on: ubuntu-latest
+    steps:                                              # <-- must use actions/checkout before mirroring!
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+      - uses: pixta-dev/repository-mirroring-action@v1
+        with:
+          target_repo_url:
+            git@gitee.com:easzlab/kubeasz.git
+          ssh_private_key:
+            ${{ secrets.SYNCGITEE }}           # 密钥 (secret)