Update rspec-github requirement from ~> 2.3.1 to ~> 2.4.0

Updates the requirements on [rspec-github](https://github.com/drieam/rspec-github) to permit the latest version.
- [Release notes](https://github.com/drieam/rspec-github/releases)
- [Commits](Drieam/rspec-github@2.3.1...2.4.0)

---
updated-dependencies:
- dependency-name: rspec-github
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

statesman.gemspec

@@ -31,7 +31,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "rails", ">= 5.2"
   spec.add_development_dependency "rake", "~> 13.0.0"
   spec.add_development_dependency "rspec", "~> 3.1"
-  spec.add_development_dependency "rspec-github", "~> 2.3.1"
+  spec.add_development_dependency "rspec-github", "~> 2.4.0"
   spec.add_development_dependency "rspec-its", "~> 1.1"
   spec.add_development_dependency "rspec-rails", "~> 3.1"
   spec.add_development_dependency "sqlite3", "~> 1.6.1"