Update README to correct Faraday gem installation command

Author: thedave42

api/ruby/find-inactive-members/README.md

@@ -24,7 +24,7 @@ cd platform-samples/api/ruby/find-inactive-members
 ### Install dependencies
 
 ```shell
-gem install octokit faraday-retry
+gem install octokit faraday
 ```
 
 ### Configure Octokit