chore(deps): bump docker/setup-buildx-action from 3 to 4 (#121)

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/release.yml

@@ -88,7 +88,7 @@ jobs:
     steps:
       - uses: actions/checkout@v7
 
-      - uses: docker/setup-buildx-action@v3
+      - uses: docker/setup-buildx-action@v4
 
       - uses: docker/login-action@v3
         if: ${{ !inputs.dry_run }}
@@ -157,7 +157,7 @@ jobs:
           pattern: digest-*
           merge-multiple: true
 
-      - uses: docker/setup-buildx-action@v3
+      - uses: docker/setup-buildx-action@v4
 
       - uses: docker/login-action@v3
         with:

.github/workflows/self-host.yml

@@ -46,7 +46,7 @@ jobs:
     steps:
       - uses: actions/checkout@v7
 
-      - uses: docker/setup-buildx-action@v3
+      - uses: docker/setup-buildx-action@v4
 
       - name: Build the image
         uses: docker/build-push-action@v7
@@ -257,7 +257,7 @@ jobs:
             echo "::notice::Upgrade test skipped — nothing here can change the upgrade path."
           fi
 
-      - uses: docker/setup-buildx-action@v3
+      - uses: docker/setup-buildx-action@v4
         if: steps.scope.outputs.run == 'true'
 
       # The version being upgraded FROM. Prefers the last release, because