Update rest-client requirement from ~> 1.8 to >= 1.8, < 3.0

Updates the requirements on [rest-client](https://github.com/rest-client/rest-client) to permit the latest version.
- [Release notes](https://github.com/rest-client/rest-client/releases)
- [Changelog](https://github.com/rest-client/rest-client/blob/master/history.md)
- [Commits](https://github.com/rest-client/rest-client/commits/v2.0.2)

Signed-off-by: dependabot[bot] <support@dependabot.com>

pushmi_pullyu.gemspec

@@ -32,7 +32,7 @@ Gem::Specification.new do |spec|
   spec.add_runtime_dependency 'rdf', '>= 1.99', '< 4.0'
   spec.add_runtime_dependency 'rdf-n3', '>= 1.99', '< 4.0'
   spec.add_runtime_dependency 'redis', '>= 3.3', '< 5.0'
-  spec.add_runtime_dependency 'rest-client', '~> 1.8'
+  spec.add_runtime_dependency 'rest-client', '>= 1.8', '< 3.0'
   spec.add_runtime_dependency 'rollbar', '~> 2.14'
 
   spec.add_development_dependency 'bundler', '~> 1.14'