Add logger dependency

This has been removed from the Ruby stdlib as of 3.5 and now needs to be
imported as a gem.

Author: alexgenco

Diff for: neovim.gemspec

@@ -21,6 +21,7 @@ Gem::Specification.new do |spec|
 
   spec.add_dependency "msgpack", "~> 1.1"
   spec.add_dependency "multi_json", "~> 1.0"
+  spec.add_dependency "logger"
 
   spec.add_development_dependency "bundler"
   spec.add_development_dependency "pry", "~> 0.14"