Runtime dependency for minor version changes only
Runtime dependency for minor version changes only

Otherwise changes in major versions like the ones done in between 3.x and 4.0 can break the Gem.
This actually happened for me when fixing `'sinatra-simple-navigation', '~> 3.7'` inside my Gemfile.
The old code loads `simple-navigation` v4 and breaks with `/app/vendor/bundle/ruby/2.0.0/gems/simple-navigation-4.0.1/lib/simple_navigation/adapters/sinatra.rb:6:in `register': wrong number of arguments (0 for 1)`
codeplant/sinatra-simple-navigation