Update rake requirement from ~> 13.1.0 to ~> 13.2.1 (#188)

Updates the requirements on [rake](https://github.com/ruby/rake) to permit the latest version.
- [Release notes](https://github.com/ruby/rake/releases)
- [Changelog](https://github.com/ruby/rake/blob/master/History.rdoc)
- [Commits](ruby/rake@v13.1.0...v13.2.1)

---
updated-dependencies:
- dependency-name: rake
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Gemfile

@@ -6,7 +6,7 @@ source 'https://rubygems.org'
 gemspec
 
 group :development, :test do
-  gem 'rake', '~> 13.1.0'
+  gem 'rake', '~> 13.2.1'
 end
 
 group :development do