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/pr-containers.yml

@@ -25,7 +25,7 @@ jobs:
 
     - name: Set up Docker Buildx
       id: buildx
-      uses: docker/setup-buildx-action@v3
+      uses: docker/setup-buildx-action@v4
       with:
         version: latest
 

.github/workflows/push.yml

@@ -37,7 +37,7 @@ jobs:
           platforms: all
       - name: Set up Docker Buildx
         id: buildx
-        uses: docker/setup-buildx-action@8d2750c68a42422c14e847fe6c8ac0403b4cbd6f # v3
+        uses: docker/setup-buildx-action@bb05f3f5519dd87d3ba754cc423b652a5edd6d2c # v4.2.0
         with:
           version: latest
       - name: Build