Bump rake minimum version to avoid CVE-2020-8130

Author: JonRowe

Gemfile

@@ -17,7 +17,7 @@ if RUBY_VERSION < '1.9.3'
 elsif RUBY_VERSION < '2.0.0'
   gem 'rake', '< 12.0.0' # rake 12 requires Ruby 2.0.0 or later
 else
-  gem 'rake', '> 12.3.2'
+  gem 'rake', '>= 12.3.3'
 end
 
 if ENV['DIFF_LCS_VERSION']