Update rake requirement from ~> 10.0 to ~> 13.0 (#11)

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...v13.0.3)

Signed-off-by: dependabot[bot] <[email protected]>

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

Gemfile.lock

@@ -48,7 +48,7 @@ GEM
     pathutil (0.16.2)
       forwardable-extended (~> 2.6)
     public_suffix (3.1.0)
-    rake (10.5.0)
+    rake (13.0.3)
     rb-fsevent (0.10.3)
     rb-inotify (0.10.0)
       ffi (~> 1.0)
@@ -80,7 +80,7 @@ PLATFORMS
 DEPENDENCIES
   bundler (~> 2.0)
   material-jekyll!
-  rake (~> 10.0)
+  rake (~> 13.0)
   rspec (~> 3.0)
 
 BUNDLED WITH

material-jekyll.gemspec

@@ -24,6 +24,6 @@ Gem::Specification.new do |spec|
 
   spec.add_runtime_dependency "jekyll", "~> 3.8"
   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