Bump docker/setup-buildx-action from 3 to 4

Bumps [docker/setup-buildx-action](https://github.com/docker/setup-buildx-action) from 3 to 4.
- [Release notes](https://github.com/docker/setup-buildx-action/releases)
- [Commits](https://github.com/docker/setup-buildx-action/compare/v3...v4)

---
updated-dependencies:
- dependency-name: docker/setup-buildx-action
  dependency-version: '4'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/build-push-backend.yml

@@ -85,7 +85,7 @@ jobs:
         run: echo "name=$(echo '${{ github.event.repository.name }}' | tr '[:upper:]' '[:lower:]')" >> $GITHUB_OUTPUT
 
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v3
+        uses: docker/setup-buildx-action@v4
         with:
           install: true
           driver-opts: image=moby/buildkit:rootless
@@ -171,7 +171,7 @@ jobs:
         run: echo "name=$(echo '${{ github.event.repository.name }}' | tr '[:upper:]' '[:lower:]')" >> $GITHUB_OUTPUT
 
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v3
+        uses: docker/setup-buildx-action@v4
 
       - name: Log in to GitHub Container Registry
         uses: docker/login-action@v3

.github/workflows/build-push-metadata_relay.yml

@@ -50,7 +50,7 @@ jobs:
         run: echo "name=$(echo '${{ github.event.repository.name }}' | tr '[:upper:]' '[:lower:]')" >> $GITHUB_OUTPUT
 
       - name:  Set up Docker Buildx
-        uses: docker/setup-buildx-action@v3
+        uses: docker/setup-buildx-action@v4
         with:
           install: true
           driver-opts: image=moby/buildkit:rootless
@@ -135,7 +135,7 @@ jobs:
         run: echo "name=$(echo '${{ github.event.repository.name }}' | tr '[:upper:]' '[:lower:]')" >> $GITHUB_OUTPUT
 
       - name:  Set up Docker Buildx
-        uses: docker/setup-buildx-action@v3
+        uses: docker/setup-buildx-action@v4
 
       - name: Log in to GitHub Container Registry
         uses: docker/login-action@v3