Remove async-io dependency.

Author: ioquatix

async-rspec.gemspec

@@ -22,7 +22,6 @@ Gem::Specification.new do |spec|
 spec.add_dependency "rspec-memory", "~> 1.0"
 
 spec.add_development_dependency "async"
-spec.add_development_dependency "async-io"
 spec.add_development_dependency "bundler"
 spec.add_development_dependency "covered"
 end