fix: Gemfile to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-RUBY-FARADAY-15253521

Author: snyk-bot

Gemfile

@@ -20,7 +20,7 @@ group :development do
   # Replaces the old lib/debug.rb and provides more features.
   gem 'debug', '>= 1.0.0'
   # module documentation
-  gem 'octokit'
+  gem 'octokit', '>= 5.0.0'
   # memory profiling
   gem 'memory_profiler'
   # cpu profiling