Rails 8.1 Deprecation Warnings - ActiveSupport::Multibyte::Chars / String#mb_chars

[rgaufman]

I'm seeing these after updating to Rails 8.1:

DEPRECATION WARNING: ActiveSupport::Multibyte::Chars is deprecated and will be removed in Rails 8.2. Use normal string methods instead. (called from Mongoid::Search::Util.normalize_keywords at /opt/homebrew/lib/ruby/gems/3.4.0/bundler/gems/mongoid_search-480349302907/lib/mongoid_search/util.rb:45)
DEPRECATION WARNING: ActiveSupport::Multibyte::Chars is deprecated and will be removed in Rails 8.2. Use normal string methods instead. (called from Mongoid::Search::Util.normalize_keywords at /opt/homebrew/lib/ruby/gems/3.4.0/bundler/gems/mongoid_search-480349302907/lib/mongoid_search/util.rb:46)
DEPRECATION WARNING: String#mb_chars is deprecated and will be removed in Rails 8.2. Use normal string methods instead. (called from Mongoid::Search::Util.normalize_keywords at /opt/homebrew/lib/ruby/gems/3.4.0/bundler/gems/mongoid_search-480349302907/lib/mongoid_search/util.rb:44)

[dblock]

Please PR a fix!

[stanley90]

Hi, here #151