Create gitcode.yml

.github/workflows/gitcode.yml

+name: 'GitHub Actions Mirror'
+
+on: [push, delete]
+
+jobs:
+  mirror_to_gitcode:
+    runs-on: ubuntu-latest
+    steps:
+      - name: 'Checkout'
+        uses: actions/checkout@v1
+      - name: 'Mirror to gitcode'
+        uses: pixta-dev/repository-mirroring-action@v1
+        with:
+          target_repo_url:
+            git@gitcode.net:csdn/skill_tree_scheme.git
+          ssh_private_key:
+            ${{ secrets.GITCODE_KEY }}