Update gemspec.yml

Co-Authored-By: Alexander Popov <alex.wayfer@gmail.com>

Author: rwojnarowski

gemspec.yml

@@ -10,5 +10,5 @@ required_ruby_version: ">= 1.9.3"
 required_rubygems_version: ">= 1.8.0"
 
 dependencies:
-  thor: ">= 0.20.3, < 2.0"
+  thor: ">= 0.18, < 2"
   bundler: ">= 1.2.0, < 3"