Relax Bundler requirements to allow 2.x

Author: karlstolley

ed..gemspec

@@ -25,6 +25,6 @@ Gem::Specification.new do |spec|
 
   spec.add_runtime_dependency "jekyll", "~> 3.6"
 
-  spec.add_development_dependency "bundler", "~> 1.16"
+  spec.add_development_dependency "bundler", ">= 1.16"
   spec.add_development_dependency "rake", "~> 10.4"
 end