chore(build): fixes docker login action credentials

.github/workflows/ci.yml

@@ -97,17 +97,17 @@ jobs:
       - uses: docker/setup-buildx-action@v2
       - uses: docker/login-action@v2
         with:
-          registry: ${{ vars.KRYSTAL_REGISTRY_HOST }}
-          username: ${{ vars.KRYSTAL_REGISTRY_USERNAME }}
-          password: ${{ secrets.KRYSTAL_REGISTRY_PASSWORD }}
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
       - uses: docker/build-push-action@v4
         with:
           push: true
           tags: |
             ghcr.io/postalserver/postal:stable
             ghcr.io/postalserver/postal:${{ needs.release-please.outputs.version }}
-          cache-from: type=local,src=/cache/krystal-identity
-          cache-to: type=local,dest=/cache/krystal-identity,mode=max
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
           target: full
           build-args: |
             VERSION=${{ needs.release-please.outputs.version }}