Update rbs requirement from ~> 3.5.1 to ~> 3.6.1

Updates the requirements on [rbs](https://github.com/ruby/rbs) to permit the latest version.
- [Release notes](https://github.com/ruby/rbs/releases)
- [Changelog](https://github.com/ruby/rbs/blob/master/CHANGELOG.md)
- [Commits](ruby/rbs@v3.5.1...v3.6.1)

---
updated-dependencies:
- dependency-name: rbs
  dependency-type: direct:development
...

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

Author: dependabot[bot]

Gemfile

@@ -5,7 +5,7 @@ gemspec
 # Development Apps
 group :development do
   group :type_check do
-    gem 'rbs', '~> 3.5.1', require: false
+    gem 'rbs', '~> 3.6.1', require: false
     gem 'steep', '~> 1.7.0', require: false
   end
   group :documentation do