Update language_server-protocol requirement from = 3.7.0.0 to = 3.15.0.1

Updates the requirements on [language_server-protocol](https://github.com/mtsmfm/language_server-protocol-ruby) to permit the latest version.
- [Release notes](https://github.com/mtsmfm/language_server-protocol-ruby/releases)
- [Changelog](https://github.com/mtsmfm/language_server-protocol-ruby/blob/master/CHANGELOG.md)
- [Commits](mtsmfm/language_server-protocol-ruby@v3.7.0.0...v3.15.0.1)

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

Author: dependabot-preview[bot]

language_server.gemspec

@@ -27,7 +27,7 @@ Gem::Specification.new do |spec|
 
   spec.required_ruby_version = ">= 2.5.0"
 
-  spec.add_dependency "language_server-protocol", "3.7.0.0"
+  spec.add_dependency "language_server-protocol", "3.15.0.1"
 
   spec.add_development_dependency "awesome_print"
   spec.add_development_dependency "benchmark-ips"