Opt-in for MFA requirement

Make the gem more secure by requiring that all privileged operations by
any of the owners require OTP.

Additionally, explicitly set minimum required Ruby version to 3.0, as
commander ~> 5.0 requires Ruby >= 3.0

Ref:
- https://guides.rubygems.org/mfa-requirement-opt-in/
- castwide/solargraph#1215

Author: tagliala

sord.gemspec

@@ -13,6 +13,10 @@ Gem::Specification.new do |spec|
   spec.homepage      = "https://github.com/AaronC81/sord"
   spec.license       = "MIT"
 
+  spec.metadata = { 'rubygems_mfa_required' => 'true' }
+
+  spec.required_ruby_version = '>= 3.0'
+
   # Specify which files should be added to the gem when it is released.
   # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
   spec.files         = Dir.chdir(File.expand_path('..', __FILE__)) do