```ruby
# frozen_string_literal: true

require 'english'

lib = File.expand_path('lib', __dir__)
$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
require 'missingly/version'

Gem::Specification.new do |spec|
  spec.name          = 'missingly'
  spec.version       = Missingly::VERSION
  spec.authors       = ['Thijs de Vries']
  spec.email         = ['moger777@gmail.com']
  spec.description   = 'A DSL for defining method missing methods'
  spec.summary       = 'A DSL for defining method missing methods'
  spec.homepage      = ''
  spec.license       = 'MIT'

  spec.files         = `git ls-files`.split($INPUT_RECORD_SEPARATOR)
  spec.executables   = spec.files.grep(%r{^bin/}) { |f| File.basename(f) }
  spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
  spec.require_paths = ['lib']

  spec.add_development_dependency 'bundler', '~> 1.3'
  spec.add_development_dependency 'coveralls'
  spec.add_development_dependency 'pry', '0.9.12'
  spec.add_development_dependency 'rake'
  spec.add_development_dependency 'rspec', '~> 2.14.0'
  spec.add_development_dependency 'rubocop'
end
```

Allow using modern version of bundler.
user
```ruby
# frozen_string_literal: true

require 'english'

lib = File.expand_path('lib', __dir__)
$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
require 'missingly/version'

Gem::Specification.new do |spec|
  spec.name          = 'missingly'
  spec.version       = Missingly::VERSION
  spec.authors       = ['Thijs de Vries']
  spec.email         = ['moger777@gmail.com']
  spec.description   = 'A DSL for defining method missing methods'
  spec.summary       = 'A DSL for defining method missing methods'
  spec.homepage      = ''
  spec.license       = 'MIT'

  spec.files         = `git ls-files`.split($INPUT_RECORD_SEPARATOR)
  spec.executables   = spec.files.grep(%r{^bin/}) { |f| File.basename(f) }
  spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
  spec.require_paths = ['lib']

  spec.add_development_dependency 'bundler'
  spec.add_development_dependency 'coveralls'
  spec.add_development_dependency 'pry', '0.9.12'
  spec.add_development_dependency 'rake'
  spec.add_development_dependency 'rspec', '~> 2.14.0'
  spec.add_development_dependency 'rubocop'
end
```
assistant