Bump dev dependency on Faraday gem to ~> 1.0.0

Why:
Trying to run specs with the old version using `bundle exec rspec` leads to an error:
```
tried to create Proc object without a block
faraday-0.9.2/lib/faraday/options.rb:153:in new:
tried to create Proc object without a block (ArgumentError)
...
../http_test_client.rb:2:in require
```

Author: keram

rspec_api_documentation.gemspec

@@ -28,7 +28,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency "rack-oauth2", "~> 1.2.2"
   s.add_development_dependency "webmock", "~> 3.8.3"
   s.add_development_dependency "rspec-its", "~> 1.2.0"
-  s.add_development_dependency "faraday", "~> 0.9.2"
+  s.add_development_dependency "faraday", "~> 1.0.0"
   s.add_development_dependency "nokogiri", "~> 1.8.4"
   s.add_development_dependency "yard", "~> 0.9.15"
   s.add_development_dependency "inch", "~> 0.8.0"