chore: Bump the required ruby version to 2.7 (#9525)

Merge pull request 9525

jekyll.gemspec

@@ -29,7 +29,7 @@ Gem::Specification.new do |s|
   s.rdoc_options     = ["--charset=UTF-8"]
   s.extra_rdoc_files = %w(README.markdown LICENSE)
 
-  s.required_ruby_version     = ">= 2.5.0"
+  s.required_ruby_version     = ">= 2.7.0"
   s.required_rubygems_version = ">= 2.7.0"
 
   s.add_dependency("csv",                           "~> 3.0")