Fix Rails edge deprecations

Ref:
- rails/rails@7a8e58b
- rails/rails#50883

Close #278

spec/support/connection.rb

@@ -5,6 +5,7 @@
 
 module ChronoTest
   AR = ActiveRecord::Base
+  AR.automatically_invert_plural_associations = true if AR.respond_to?(:automatically_invert_plural_associations)
   log = ENV['VERBOSE'].present? ? $stderr : 'spec/debug.log'.tap { |f| File.open(f, 'ab') { |ft| ft.truncate(0) } }
   AR.logger = ::Logger.new(log).tap do |l|
     l.level = 0