Rakefile in hoe-3.20.0 vs Rakefile in hoe-3.21.0

@@ -16,9 +16,10 @@
 
   license "MIT"
 
   pluggable!
   require_rubygems_version ">= 1.4"
+  require_ruby_version "~> 2.1"
 
   dependency "rake", [">= 0.8", "< 15.0"] # FIX: to force it to exist pre-isolate
 end
 
 task :plugins do