Remove @request_store@ gem (#39110).

Patch by Takashi Kato.

git-svn-id: https://svn.redmine.org/redmine/trunk@22474 e93f8b46-1217-0410-a6f0-8f06a7374b81

Gemfile

@@ -4,7 +4,6 @@ ruby '>= 2.7.0', '< 3.3.0'
 
 gem 'rails', '6.1.7.6'
 gem 'rouge', '~> 4.2.0'
-gem 'request_store', '~> 1.5.0'
 gem 'mini_mime', '~> 1.1.0'
 gem "actionpack-xml_parser"
 gem 'roadie-rails', '~> 3.1.0'