Bump json from 2.7.6 to 2.8.1 in /gemfile_steep

Bumps [json](https://github.com/ruby/json) from 2.7.6 to 2.8.1.
- [Release notes](https://github.com/ruby/json/releases)
- [Changelog](https://github.com/ruby/json/blob/master/CHANGES.md)
- [Commits](ruby/json@v2.7.6...v2.8.1)

---
updated-dependencies:
- dependency-name: json
  dependency-type: indirect
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

gemfile_steep/Gemfile.lock

@@ -26,7 +26,7 @@ GEM
     fileutils (1.7.3)
     i18n (1.14.6)
       concurrent-ruby (~> 1.0)
-    json (2.7.6)
+    json (2.8.1)
     language_server-protocol (3.17.0.3)
     listen (3.9.0)
       rb-fsevent (~> 0.10, >= 0.10.3)