Prepare to release v2.6.9

CHANGELOG.rdoc

+== 2.6.9
+* Support foreigh key (#241)
+* Check if model has skip tag in annotate_model_file (#167)
+* Fix issue where serializer-related flags weren't being honored (#246)
+* Prefer SQL column type over normalized AR type (#231)
+
 == 2.6.8
 * Nothing annotated unless options[:model_dir] is specified, #234
 

lib/annotate/version.rb

 module Annotate
   def self.version
-    '2.6.8'
+    '2.6.9'
   end
 end