Allow testing with bundler 2

Author: deivid-rodriguez

thor.gemspec

@@ -4,7 +4,7 @@ $LOAD_PATH.unshift lib unless $LOAD_PATH.include?(lib)
 require "thor/version"
 
 Gem::Specification.new do |spec|
-  spec.add_development_dependency "bundler", "~> 1.0"
+  spec.add_development_dependency "bundler", ">= 1.0", "< 3"
   spec.authors = ["Yehuda Katz", "José Valim"]
   spec.description = "Thor is a toolkit for building powerful command-line interfaces."
   spec.email = "[email protected]"