Remove unused require

`require 'active_support/core_ext/string/filters'` was added in b3bfa361. However, it is no longer needed from 3ae98181.

activerecord/lib/active_record/relation/query_methods.rb

@@ -3,7 +3,6 @@
 require "active_record/relation/where_clause"
 require "active_record/relation/where_clause_factory"
 require 'active_model/forbidden_attributes_protection'
-require 'active_support/core_ext/string/filters'
 
 module ActiveRecord
   module QueryMethods