chore(deps): 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](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>

Author: dependabot[bot]

.github/workflows/agent-image-smoke.yaml

@@ -30,7 +30,7 @@ jobs:
 
       - name: Set up Buildx
         if: steps.guard.outputs.skip != 'true'
-        uses: docker/setup-buildx-action@v3
+        uses: docker/setup-buildx-action@v4
 
       - name: Read pinned HERMES_VERSION from uv.lock
         if: steps.guard.outputs.skip != 'true'

.github/workflows/agent-image.yaml

@@ -48,7 +48,7 @@ jobs:
         uses: docker/setup-qemu-action@v4
 
       - name: Set up Buildx
-        uses: docker/setup-buildx-action@v3
+        uses: docker/setup-buildx-action@v4
 
       - name: Log in to GHCR
         uses: docker/login-action@v4

.github/workflows/build.yaml

@@ -13,7 +13,7 @@ jobs:
       packages: write
     steps:
       - uses: actions/checkout@v6
-      - uses: docker/setup-buildx-action@v3
+      - uses: docker/setup-buildx-action@v4
       # Multi-arch builds for releases happen in release.yaml via
       # docker/build-push-action (uses Go cross-compile under
       # BUILDPLATFORM, not QEMU). This job is a fast PR smoke test:

.github/workflows/release.yaml

@@ -37,7 +37,7 @@ jobs:
           cache: true
 
       - 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@v4