chore(deps): update docker/setup-buildx-action action to v4

Author: renovate[bot]

.github/workflows/grass-tests.yml

@@ -16,7 +16,7 @@ jobs:
     - name: Checkout
       uses: actions/checkout@v6
     - name: Set up Docker Buildx
-      uses: docker/setup-buildx-action@v3
+      uses: docker/setup-buildx-action@v4
     - name: add Dockerfile and test skript
       run: |
         ( mkdir -p test-docker && cd test-docker && \