ci(deps): Bump docker/setup-buildx-action from 3.6.1 to 4.0.0

Bumps [docker/setup-buildx-action](https://github.com/docker/setup-buildx-action) from 3.6.1 to 4.0.0.
- [Release notes](https://github.com/docker/setup-buildx-action/releases)
- [Commits](docker/setup-buildx-action@v3.6.1...4d04d5d)

---
updated-dependencies:
- dependency-name: docker/setup-buildx-action
  dependency-version: 4.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/docker-e2e.yml

@@ -31,7 +31,7 @@ jobs:
 
       # ── 2. Set up Docker Buildx ──────────────────────────────────────
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@988b5a0280414f521da01fcc63a27aeeb4b104db  # v3.6.1
+        uses: docker/setup-buildx-action@4d04d5d9486b7bd6fa91e7baf45bbb4f8b9deedd  # v4.0.0
 
       # ── 3. Build image (no push) ─────────────────────────────────────
       - name: Build Dockerfile.complete

.github/workflows/health-check.yml

@@ -102,7 +102,7 @@ jobs:
           pip install checkov>=3.1.0
 
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@c47758b77c9736f4b2ef4073d4d51994fabfe349  # v3.7.1
+        uses: docker/setup-buildx-action@4d04d5d9486b7bd6fa91e7baf45bbb4f8b9deedd  # v4.0.0
 
       - name: Run health check
         id: health-check

.github/workflows/integration-tests.yml

@@ -153,7 +153,7 @@ jobs:
           pip install pytest pytest-cov
 
       - name: Set up Docker
-        uses: docker/setup-buildx-action@8d2750c68a42422c14e847fe6c8ac0403b4cbd6f  # v3
+        uses: docker/setup-buildx-action@4d04d5d9486b7bd6fa91e7baf45bbb4f8b9deedd  # v4.0.0
 
       - name: Build sandbox image (if needed)
         run: |

.github/workflows/publish-container.yml

@@ -26,7 +26,7 @@ jobs:
           fetch-depth: 0  # Full history for better layer caching
 
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@988b5a0280414f521da01fcc63a27aeeb4b104db  # v3.6.1
+        uses: docker/setup-buildx-action@4d04d5d9486b7bd6fa91e7baf45bbb4f8b9deedd  # v4.0.0
         with:
           platforms: linux/amd64,linux/arm64
           driver-opts: |