explicit docker install?

.gitea/workflows/build.yaml

@@ -25,6 +25,13 @@ jobs:
         username: ${{ secrets.docker_username }}
         password: ${{ secrets.docker_password }}
 
+    - name: Install Docker
+      run: |
+        curl -fsSL https://get.docker.com -o get-docker.sh
+        sh get-docker.sh
+        sudo usermod -aG docker $USER
+        sudo systemctl start docker
+        sudo systemctl enable docker
 
     - name: Build
       uses: https://github.com/docker/build-push-action@v2