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/v1.8.0)

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

calagator.gemspec

@@ -42,7 +42,7 @@ Gem::Specification.new do |s|
   s.add_dependency 'rails-observers'
   s.add_dependency 'rails_autolink', '~> 1.1'
   s.add_dependency 'recaptcha', '~> 3.3.0'
-  s.add_dependency 'rest-client', '~> 1.8'
+  s.add_dependency 'rest-client', '>= 1.8', '< 3.0'
   s.add_dependency 'ri_cal', '~> 0.8.8'
   s.add_dependency 'sassc-rails', '~> 1.3'
   s.add_dependency 'sunspot_rails', '~> 2.1'