Update rake requirement to ~> 12.2

Updates the requirements on [rake](https://github.com/ruby/rake) to permit the latest version.
- [Changelog](https://github.com/ruby/rake/blob/master/History.rdoc)

Author: dependabot[bot]

language_server.gemspec

@@ -38,5 +38,5 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "minitest-color"
   spec.add_development_dependency "minitest-power_assert"
   spec.add_development_dependency "pry-byebug"
-  spec.add_development_dependency "rake", "~> 10.0"
+  spec.add_development_dependency "rake", "~> 12.2"
 end