Remove bundler from gemspec

Author: maxim

portrayal.gemspec

@@ -21,7 +21,6 @@ Gem::Specification.new do |spec|
   end
   spec.require_paths = ['lib']
 
-  spec.add_development_dependency 'bundler', '~> 2.4'
   spec.add_development_dependency 'rake', '~> 13.0'
   spec.add_development_dependency 'rspec', '~> 3.12'
   spec.add_development_dependency 'pry', '~> 0.14'