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

Gem::Specification.new do |spec|
  spec.name          = "ruboty-leveldb"
  spec.version       = Ruboty::Leveldb::VERSION
  spec.authors       = ["nownabe"]
  spec.email         = ["nownabe@gmail.com"]
  spec.summary       = %q{Store Ruboty's memory in LevelDB.}
  spec.homepage      = "https://github.com/nownabe/ruboty-leveldb"
  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 "ruboty"
  spec.add_dependency "leveldb"

  spec.add_development_dependency "bundler", "~> 1.7"
  spec.add_development_dependency "rake", "~> 10.0"
end
```

Update rake requirement from ~> 10.0 to ~> 13.0
user
```ruby
# coding: utf-8
lib = File.expand_path('../lib', __FILE__)
$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
require 'ruboty/leveldb/version'

Gem::Specification.new do |spec|
  spec.name          = "ruboty-leveldb"
  spec.version       = Ruboty::Leveldb::VERSION
  spec.authors       = ["nownabe"]
  spec.email         = ["nownabe@gmail.com"]
  spec.summary       = %q{Store Ruboty's memory in LevelDB.}
  spec.homepage      = "https://github.com/nownabe/ruboty-leveldb"
  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 "ruboty"
  spec.add_dependency "leveldb"

  spec.add_development_dependency "bundler", "~> 1.7"
  spec.add_development_dependency "rake", "~> 13.0"
end
```
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