chore(deps): bump docker/setup-buildx-action from 3 to 4 (#25)

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](docker/setup-buildx-action@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>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -155,7 +155,7 @@ jobs:
         uses: actions/checkout@v5
 
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v3
+        uses: docker/setup-buildx-action@v4
 
       - name: Build authz service
         run: docker build -t keep/authz -f services/authz/Dockerfile .

.github/workflows/deploy.yml

@@ -20,7 +20,7 @@ jobs:
         uses: docker/setup-qemu-action@v3
 
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v3
+        uses: docker/setup-buildx-action@v4
 
       - name: Login to GitHub Container Registry
         uses: docker/login-action@v3

.github/workflows/smoke-tests.yml

@@ -11,7 +11,7 @@ jobs:
         uses: actions/checkout@v5
 
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v3
+        uses: docker/setup-buildx-action@v4
 
       - name: Run smoke tests
         run: |