Fix test for rails edge

[dylanahsmith]

CI is failing on Rails Edge with the following failure

  1) Failure:
IndexCacheTest#test_fetch_with_unique_adds_limit_clause [/opt/hostedtoolcache/Ruby/3.0.4/x64/lib/ruby/gems/3.0.0/bundler/gems/rails-18da7b6ba71c/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:589]:
unexpected invocation: #<ActiveRecord::ConnectionAdapters::Mysql2Adapter:0x2e68>.exec_query("SELECT `items`.`id` FROM `items` WHERE `items`.`title` = ? AND `items`.`id` = ? LIMIT ?", "Item Pluck", [#<ActiveRecord::Relation::QueryAttribute:0x192f8>, #<ActiveRecord::Relation::QueryAttribute:0x19320>, #<ActiveModel::Attribute::WithCastValue:0x19348>], {:prepare => true})
unsatisfied expectations:
- expected exactly once, invoked never: #<ActiveRecord::ConnectionAdapters::Mysql2Adapter:0x2e68>.exec_query(regexp_matches(/ LIMIT 1\Z/i), any_parameters)

Since LIMIT 1 isn't matching LIMIT ?, so I fixed the test regex to allow that.