Update rake requirement from ~> 10.0 to ~> 13.0 (#4)

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/compare/v10.5.0...v13.0.1)

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

Gemfile.lock

@@ -54,7 +54,7 @@ GEM
       omniauth (~> 1.9)
     public_suffix (3.0.3)
     rack (2.0.8)
-    rake (10.5.0)
+    rake (13.0.1)
     rspec (3.8.0)
       rspec-core (~> 3.8.0)
       rspec-expectations (~> 3.8.0)
@@ -89,7 +89,7 @@ PLATFORMS
 DEPENDENCIES
   bundler (~> 1.16)
   omniauth-keycloak!
-  rake (~> 10.0)
+  rake (~> 13.0)
   rspec (~> 3.0)
   simplecov (~> 0.16.1)
   webmock (~> 3.4.2)

omniauth-keycloak.gemspec

@@ -28,7 +28,7 @@ Gem::Specification.new do |spec|
   spec.add_dependency 'json-jwt', '~> 1.11'
 
   spec.add_development_dependency "bundler", "~> 1.16"
-  spec.add_development_dependency "rake", "~> 10.0"
+  spec.add_development_dependency "rake", "~> 13.0"
   spec.add_development_dependency "rspec", "~> 3.0"
   spec.add_development_dependency 'simplecov', '~> 0.16.1'
   spec.add_development_dependency 'webmock', '~> 3.4.2'