fix gemspec date

Author: Mike Hagedorn

chargify_api_ares.gemspec

@@ -5,7 +5,7 @@ Gem::Specification.new do |s|
 
   s.name        = 'chargify_api_ares'
   s.version     = '1.4.10'
-  s.date        = '2016-08-22'
+  s.date        = '2017-05-12'
   s.summary     = 'A Chargify API wrapper for Ruby using ActiveResource'
   s.description = ''
   s.authors     = ["Chargify Development Team"]