Fix extra blank line when adding rubocop-rails-omakase and brakeman (rails#50626)

Author: akhilgkrishnan

railties/lib/rails/generators/rails/app/templates/Gemfile.tt

@@ -37,14 +37,14 @@ group :development, :test do
   # See https://guides.rubyonrails.org/debugging_rails_applications.html#debugging-with-the-debug-gem
   gem "debug", platforms: %i[ mri <%= bundler_windows_platforms %> ]
 <%- unless options.skip_brakeman? -%>
+
   # Static analysis for security vulnerabilities [https://brakemanscanner.org/]
   gem "brakeman", require: false
-
 <%- end -%>
 <%- unless options.skip_rubocop? -%>
+
   # Omakase Ruby styling [https://github.com/rails/rubocop-rails-omakase/]
   gem "rubocop-rails-omakase", require: false
-
 <%- end -%>
 end
 <% end -%>