ci: replace actions/checkout with raw git clone

.gitea/workflows/deploy.yml

@@ -12,7 +12,12 @@ jobs:
   build-deploy:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - name: Checkout
+        run: |
+          git init -q
+          git remote add origin "https://oauth2:${{ secrets.GITEA_TOKEN }}@gitea.mystmec.com/${{ github.repository }}.git"
+          git fetch --depth 1 origin "${{ github.sha }}"
+          git checkout -q FETCH_HEAD
 
       - name: Login to Gitea Container Registry
         run: |