Update rake requirement from ~> 10.0 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](https://github.com/ruby/rake/commits/v12.3.2)

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

tdigest.gemspec

@@ -30,7 +30,7 @@ Gem::Specification.new do |spec|
   end
 
   spec.add_development_dependency 'bundler', '~> 1.10'
-  spec.add_development_dependency 'rake', '~> 10.0'
+  spec.add_development_dependency 'rake', '~> 12.3'
   spec.add_development_dependency 'minitest', '~> 5.8'
   spec.add_development_dependency 'coveralls', '~> 0.8.10'
   spec.add_development_dependency 'simplecov', '~> 0.11.1'