Update rake requirement from ~> 10.0 to ~> 13.0

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@v10.5.0...v13.0.1)

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

Author: dependabot[bot]

Gemfile.lock

@@ -23,7 +23,7 @@ GEM
       concurrent-ruby (~> 1.0)
     minitest (5.11.3)
     multi_xml (0.6.0)
-    rake (10.5.0)
+    rake (13.0.1)
     rspec (3.8.0)
       rspec-core (~> 3.8.0)
       rspec-expectations (~> 3.8.0)
@@ -47,7 +47,7 @@ PLATFORMS
 DEPENDENCIES
   bundler (~> 2.0)
   open_invoice!
-  rake (~> 10.0)
+  rake (~> 13.0)
   rspec (~> 3.0)
 
 BUNDLED WITH

open_invoice.gemspec

@@ -41,6 +41,6 @@ Gem::Specification.new do |spec|
   spec.add_runtime_dependency "activesupport"
 
   spec.add_development_dependency "bundler", "~> 2.0"
-  spec.add_development_dependency "rake", "~> 10.0"
+  spec.add_development_dependency "rake", "~> 13.0"
   spec.add_development_dependency "rspec", "~> 3.0"
 end