```ruby
# coding: utf-8
lib = File.expand_path('../lib', __FILE__)
$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
require 'dynamic_fields_for_rails/version'

Gem::Specification.new do |spec|
  spec.name          = "dynamic_fields_for_rails"
  spec.version       = DynamicFieldsForRails::VERSION
  spec.authors       = ["Marten Klitzke"]
  spec.email         = ["m.klitzke@gmail.com"]
  spec.description   = 'Dynamic fields helper for Rails.'
  spec.summary       = 'Helper for nested forms with dynamic fields.'
  spec.homepage      = "https://github.com/mortik/dynamic_fields_for_rails"
  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 "rake", '~> 0'
  spec.add_development_dependency "mocha", '~> 0'
  spec.add_development_dependency "sqlite3", '~> 0'

  spec.add_dependency "rails", '>= 3.0.0'
end
```

Set max Version of Rails dependency to 6
user
```ruby
# coding: utf-8
lib = File.expand_path('../lib', __FILE__)
$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
require 'dynamic_fields_for_rails/version'

Gem::Specification.new do |spec|
  spec.name          = "dynamic_fields_for_rails"
  spec.version       = DynamicFieldsForRails::VERSION
  spec.authors       = ["Marten Klitzke"]
  spec.email         = ["m.klitzke@gmail.com"]
  spec.description   = 'Dynamic fields helper for Rails.'
  spec.summary       = 'Helper for nested forms with dynamic fields.'
  spec.homepage      = "https://github.com/mortik/dynamic_fields_for_rails"
  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 "rake", '~> 0'
  spec.add_development_dependency "mocha", '~> 0'
  spec.add_development_dependency "sqlite3", '~> 0'

  spec.add_dependency "rails", '>= 3.0.0', '< 6.0.0'
end
```
assistant