build: docker cache for test workflow (#108)

.github/workflows/test.yml

@@ -20,8 +20,14 @@ jobs:
         uses: docker/setup-buildx-action@v3
 
       - name: Build test image
-        run: |
-          docker build --target builder -t imagorvideo-test .
+        uses: docker/build-push-action@v5
+        with:
+          context: .
+          target: builder
+          tags: imagorvideo-test
+          load: true
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
 
       - name: Run tests in Docker
         run: |