Chore: Rubocop 0.49.0 (#516)

* Rubocoping

github_changelog_generator.gemspec

@@ -1,5 +1,6 @@
 # coding: utf-8
 # frozen_string_literal: true
+
 lib = File.expand_path("../lib", __FILE__)
 $LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
 require "github_changelog_generator/version"
@@ -18,7 +19,7 @@ Gem::Specification.new do |spec|
   spec.homepage = "https://github.com/skywinder/Github-Changelog-Generator"
   spec.license = "MIT"
 
-  spec.files = Dir["{bin,lib,man,spec}/**/*"] + %w(LICENSE Rakefile README.md)
+  spec.files = Dir["{bin,lib,man,spec}/**/*"] + %w[LICENSE Rakefile README.md]
 
   spec.executables   = spec.files.grep(%r{^bin/}) { |f| File.basename(f) }
   spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})