add ssh key install to deploy

.gitea/workflows/deploy.yml

@@ -10,6 +10,10 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - uses: actions/checkout@v5
+      - name: Install SSH key
+        uses: shimataro/ssh-key-action@v2
+        with:
+          key: ${{ secrets.SSH_KEY }}
       - name: Install dependencies for Nix setup action
         run: |
           apt update -y