Bump docker/setup-buildx-action from 3 to 4 (#54)

Author: dependabot[bot]

.github/workflows/docker.yml

@@ -28,7 +28,7 @@ jobs:
     steps:
       - uses: actions/checkout@v6
       - uses: docker/setup-qemu-action@v4
-      - uses: docker/setup-buildx-action@v3
+      - uses: docker/setup-buildx-action@v4
       - uses: docker/login-action@v4
         with:
           registry: ${{ env.REGISTRY }}