Build(deps-dev): Bump minitest from 5.20.0 to 5.21.1 (#25257)

Bumps [minitest](https://github.com/minitest/minitest) from 5.20.0 to 5.21.1.
- [Changelog](https://github.com/minitest/minitest/blob/master/History.rdoc)
- [Commits](https://github.com/minitest/minitest/compare/v5.20.0...v5.21.1)

---
updated-dependencies:
- dependency-name: minitest
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Gemfile.lock

@@ -235,7 +235,7 @@ GEM
     mini_suffix (0.3.3)
       ffi (~> 1.9)
     minio_runner (0.1.2)
-    minitest (5.20.0)
+    minitest (5.21.1)
     mocha (2.1.0)
       ruby2_keywords (>= 0.0.5)
     msgpack (1.7.2)