fix: hardcode git.ampbox.io in checkout (runner has localhost:3000)

Runner's instance config points to localhost:3000 instead of the
public URL. Bypass the checkout action and clone directly from
git.ampbox.io.

🤖 Generated with [Amplifier](https://github.com/microsoft/amplifier)

Co-Authored-By: Amplifier <240397093+microsoft-amplifier@users.noreply.github.com>

.gitea/workflows/deploy.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: http://gitea.com/actions/checkout@v4
+        run: git clone --depth 1 --branch main https://git.ampbox.io/${{ github.repository }}.git .
 
       - name: Build and deploy
         run: |