Update rake requirement from ~> 10.4 to ~> 12.3

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@v10.4.0...v12.3.3)

Signed-off-by: dependabot[bot] <support@github.com>

steam-condenser.gemspec

@@ -18,7 +18,7 @@ Gem::Specification.new do |s|
   s.add_dependency 'rexml', '~> 3.2'
 
   s.add_development_dependency 'mocha', '~> 1.1'
-  s.add_development_dependency 'rake', '~> 10.4'
+  s.add_development_dependency 'rake', '~> 12.3'
   s.add_development_dependency 'shoulda-context', '~> 1.2'
   s.add_development_dependency 'test-unit', '~> 3.0'
   s.add_development_dependency 'yard', '~> 0.8'