docker build - use --cache-from

See #208

Author: macbre

.github/workflows/dockerimage.yml

@@ -19,5 +19,7 @@ jobs:
         COMPOSE_DOCKER_CLI_BUILD: "1"
         DOCKER_BUILDKIT: "1"
       run: |
-        docker build . --tag ${{ github.repository }}
+        docker build . \
+          --cache-from macbre/index-digest:latest \
+          --tag ${{ github.repository }}
         docker images