Merge pull request #227 from pmarsceill/dependabot/bundler/rake-gte-12.3.1-and-lt-13.1.0

Update rake requirement from ~> 12.3.1 to >= 12.3.1, < 13.1.0

just-the-docs.gemspec

@@ -16,6 +16,6 @@ Gem::Specification.new do |spec|
   spec.add_runtime_dependency "bundler", "~> 2.1.4"
   spec.add_runtime_dependency "jekyll", ">= 3.8.5", "< 4.1.0"
   spec.add_runtime_dependency "jekyll-seo-tag", "~> 2.0"
-  spec.add_runtime_dependency "rake", "~> 12.3.1"
+  spec.add_runtime_dependency "rake", ">= 12.3.1", "< 13.1.0"
 
 end