ci: cache docker layers

.gitea/workflows/docker-build.yml

@@ -14,6 +14,14 @@ jobs:
     - name: Set up Docker Buildx
       uses: docker/setup-buildx-action@v2
 
+    - name: Cache Docker layers
+      uses: actions/cache@v3
+      with:
+        path: /tmp/.buildx-cache
+        key: ${{ runner.os }}-buildx-${{ hashFiles('**/requirements.txt') }}-${{ hashFiles('**/package*.json') }}
+        restore-keys: |
+          ${{ runner.os }}-buildx-
+
     - name: Login to Docker Registry
       uses: docker/login-action@v2
       with: