build(deps-dev): bump minitest from 5.20.0 to 5.21.1

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](minitest/minitest@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] <[email protected]>

Gemfile.lock

@@ -17,7 +17,7 @@ GEM
     iniparse (1.5.0)
     json (2.7.1)
     language_server-protocol (3.17.0.3)
-    minitest (5.20.0)
+    minitest (5.21.1)
     minitest-reporters (1.6.1)
       ansi
       builder