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

Gem::Specification.new do |spec|
  spec.name          = "event_sourcing"
  spec.version       = EventSourcing::VERSION
  spec.authors       = ["Rodrigo Alvarez"]
  spec.email         = ["papipo@gmail.com"]
  spec.summary       = %q{Actor based EventSourcing framework for ruby.}
  spec.homepage      = "https://github.com/Papipo/event_sourcing"
  spec.license       = "MIT"

  spec.files         = `git ls-files -z`.split("\x0")
  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_dependency "values"
  spec.add_dependency "concurrent-ruby", "~> 0.7.1"

  spec.add_development_dependency "bundler", "~> 1.6"
  spec.add_development_dependency "rake"
  spec.add_development_dependency "rspec"
  spec.add_development_dependency "spinach"
  spec.add_development_dependency "guard-spinach"
  spec.add_development_dependency "guard-rspec"
end
```

Make required gem versions more specific
user
```ruby
# coding: utf-8
lib = File.expand_path('../lib', __FILE__)
$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
require 'event_sourcing/version'

Gem::Specification.new do |spec|
  spec.name          = "event_sourcing"
  spec.version       = EventSourcing::VERSION
  spec.authors       = ["Rodrigo Alvarez"]
  spec.email         = ["papipo@gmail.com"]
  spec.summary       = %q{Actor based EventSourcing framework for ruby.}
  spec.homepage      = "https://github.com/Papipo/event_sourcing"
  spec.license       = "MIT"

  spec.files         = `git ls-files -z`.split("\x0")
  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_dependency "values", "~> 1.5"
  spec.add_dependency "concurrent-ruby", "~> 0.7.1"

  spec.add_development_dependency "bundler", "~> 1.7"
  spec.add_development_dependency "rake"
  spec.add_development_dependency "rspec",   "~> 3.1"
  spec.add_development_dependency "spinach", "~> 0.8.10"
  spec.add_development_dependency "guard-spinach"
  spec.add_development_dependency "guard-rspec"
end
```
assistant