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/ponder-image.yml

@@ -39,7 +39,7 @@ jobs:
       - name: Set image name
         run: echo "IMAGE_NAME=ghcr.io/${GITHUB_REPOSITORY,,}-ponder" >> "$GITHUB_ENV"
 
-      - uses: docker/setup-buildx-action@v3
+      - uses: docker/setup-buildx-action@v4
 
       - uses: docker/login-action@v3
         if: github.event_name != 'pull_request'