build(deps): bump docker/build-push-action from 3 to 4 (#2106)

Bumps [docker/build-push-action](https://github.com/docker/build-push-action) from 3 to 4.
- [Release notes](https://github.com/docker/build-push-action/releases)
- [Commits](docker/build-push-action@v3...v4)

---
updated-dependencies:
- dependency-name: docker/build-push-action
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

.github/workflows/docker.yml

@@ -72,7 +72,7 @@ jobs:
 
       - name: Test build
         id: docker_build_test
-        uses: docker/build-push-action@v3
+        uses: docker/build-push-action@v4
         with:
           context: .
           file: docker/Dockerfile
@@ -110,7 +110,7 @@ jobs:
         # every PR will trigger a push event on main, so check the push event is actually coming from main
         if: github.event_name == 'push' && github.ref == 'refs/heads/main' && github.repository == 'scikit-hep/pyhf'
         id: docker_build_latest
-        uses: docker/build-push-action@v3
+        uses: docker/build-push-action@v4
         with:
           context: .
           file: docker/Dockerfile
@@ -125,7 +125,7 @@ jobs:
       - name: Build and publish to registry with release tag
         if: github.event_name == 'release' && github.event.action == 'published' && github.repository == 'scikit-hep/pyhf'
         id: docker_build_release
-        uses: docker/build-push-action@v3
+        uses: docker/build-push-action@v4
         with:
           context: .
           file: docker/Dockerfile