Add cache to docker action buildfile

Signed-off-by: trivernis <trivernis@protonmail.com>

.github/workflows/docker.yml

@@ -16,6 +16,13 @@ jobs:
       -
         name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v1
+      - name: Cache Docker layers
+        uses: actions/cache@v2
+        with:
+          path: /tmp/.buildx-cache
+          key: ${{ runner.os }}-buildx-${{ github.sha }}
+          restore-keys: |
+            ${{ runner.os }}-buildx-
       -
         name: Login to DockerHub
         uses: docker/login-action@v1