fix: use gha as cache backend for docker images

Signed-off-by: Anupam Kumar <kyteinsky@gmail.com>

Author: kyteinsky

.github/workflows/integration-test-k8s.yml

@@ -211,6 +211,13 @@ jobs:
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@e468171a9de216ec08956ac3ada2f0791b6bd435 # v3
 
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@184bdaa0721073962dff0199f1fb9940f07167d1 # v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
       - name: Build the context_chat_backend cpu image
         uses: docker/build-push-action@263435318d21b8e681c14492fe198d362a7d2c83 # v6
         with:
@@ -220,8 +227,8 @@ jobs:
           tags: ccb-cpu:latest
           target: runtime-cpu
           load: true
-          cache-from: type=registry,ref=nextcloud/context_chat_backend:cpu-build-cache,compression=zstd,mode=max
-          cache-to: type=registry,ref=nextcloud/context_chat_backend:cpu-build-cache
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
 
       - name: Pre-load CCB ExApp image into k3s
         run: docker save ccb-cpu:latest | sudo k3s ctr images import -