Builder docker cache to registry

Author: blahgeek

.github/workflows/_prepare-docker.yml

@@ -13,15 +13,21 @@ jobs:
     - name: Checkout
       uses: actions/checkout@v4
 
+    - name: Login to Docker Hub
+      uses: docker/login-action@v3
+      with:
+        username: blahgeek
+        password: ${{ secrets.DOCKERHUB_TOKEN }}
+
     - name: Set up Docker Buildx
       uses: docker/setup-buildx-action@v3
 
     - name: Build and export
-      uses: docker/build-push-action@v5
+      uses: docker/build-push-action@v6
       with:
         context: .
-        cache-from: type=gha
-        cache-to: type=gha,mode=max
+        cache-from: type=registry,ref=blahgeek/emacs-appimage-builder:${{ inputs.arch }}-cache
+        cache-to: type=registry,ref=blahgeek/emacs-appimage-builder:${{ inputs.arch }}-cache,mode=max
         tags: builder-image:latest
         outputs: type=docker,dest=/tmp/${{ inputs.arch }}-builder-image.tar