Gemspec improvements (#109)

* Specify actual authors of the gem

* Fix and improve gem's `summary` and `description`

* Remove useless `require_paths` and `test_files`

* Improve required Ruby version lock, avoid 3.0

* Add versions locks for dependencies

It's very dangerous and unstable to have dependencies without any version lock,
they may update at any time and without backward compatibility.

Author: AlexWayfer

codecov.gemspec

@@ -2,25 +2,23 @@
 
 Gem::Specification.new do |s|
   s.name                  = 'codecov'
-  s.authors               = ['codecov']
-  s.description           = 'hosted code coverage'
+  s.authors               = ['Steve Peak', 'Tom Hu']
+  s.summary               = 'Hosted code coverage'
+  s.description           = 'Hosted code coverage Ruby reporter.'
   s.email                 = ['[email protected]']
   s.files                 = ['lib/codecov.rb']
   s.homepage              = 'https://github.com/codecov/codecov-ruby'
   s.license               = 'MIT'
   s.platform              = Gem::Platform::RUBY
-  s.require_paths         = ['lib']
-  s.required_ruby_version = '>=2.4'
-  s.summary               = 'hosted code coverage ruby/rails reporter'
-  s.test_files            = ['test/test_codecov.rb']
+  s.required_ruby_version = '~> 2.4'
   s.version               = '0.2.12'
 
-  s.add_dependency 'simplecov'
+  s.add_dependency 'simplecov', '~> 0.18.0'
 
-  s.add_development_dependency 'minitest'
-  s.add_development_dependency 'minitest-ci'
-  s.add_development_dependency 'mocha'
-  s.add_development_dependency 'rake'
-  s.add_development_dependency 'rubocop'
-  s.add_development_dependency 'webmock'
+  s.add_development_dependency 'minitest', '~> 5.0'
+  s.add_development_dependency 'minitest-ci', '~> 3.0'
+  s.add_development_dependency 'mocha', '~> 1.0'
+  s.add_development_dependency 'rake', '~> 13.0'
+  s.add_development_dependency 'rubocop', '~> 1.0'
+  s.add_development_dependency 'webmock', '~> 3.0'
 end