Make Person.search_query_string public.

Accessibility of private/protected class methods in :scope is deprecated and will be removed in Rails 6.0.

app/models/person.rb

@@ -209,7 +209,7 @@ class Person < ApplicationRecord
     self.guid
   end
 
-  private_class_method def self.search_query_string(query)
+  def self.search_query_string(query)
     query = query.downcase
     like_operator = AppConfig.postgres? ? "ILIKE" : "LIKE"