Update rake requirement from ~> 10 to ~> 13 (#310)

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...v13.1.0)

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

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

Gemfile.lock

@@ -62,7 +62,7 @@ GEM
       nokogiri (>= 1.6)
     rails-html-sanitizer (1.5.0)
       loofah (~> 2.19, >= 2.19.1)
-    rake (10.5.0)
+    rake (13.1.0)
     rexml (3.2.5)
     thor (0.20.3)
     thread_safe (0.3.6)
@@ -78,7 +78,7 @@ DEPENDENCIES
   adiwg-mdtranslator!
   bundler (~> 2)
   minitest (~> 5)
-  rake (~> 10)
+  rake (~> 13)
 
 BUNDLED WITH
    2.4.21

adiwg-mdtranslator.gemspec

@@ -26,7 +26,7 @@ Gem::Specification.new do |spec|
    spec.required_ruby_version = '>= 2.3'
 
    spec.add_development_dependency "bundler", "~> 2"
-   spec.add_development_dependency "rake", "~> 10"
+   spec.add_development_dependency "rake", "~> 13"
    spec.add_development_dependency "minitest", "~> 5"
 
    spec.add_runtime_dependency "json", "~> 2.0"