Use omniauth 1.9 to ensure latest security updates

Author: tmilewski

omniauth-oauth2.gemspec

@@ -4,7 +4,7 @@ require "omniauth-oauth2/version"
 
 Gem::Specification.new do |gem|
   gem.add_dependency "oauth2",     "~> 1.1"
-  gem.add_dependency "omniauth",   "~> 1.2"
+  gem.add_dependency "omniauth",   "~> 1.9"
 
   gem.add_development_dependency "bundler", "~> 1.0"