v4.25.9

• Suppress warning messages on Ruby 2.7. Thanks to @koic
  • Suppress keyword argument warnings in Ruby 2.7 #200
  • Suppress a Ruby warning for Object#=~ and bug fix to match patterns #201
• #203 Replace .+ with [^ ] on some large regular expressions for serious performance reason.
• #204 Suport Null MX (RFC7505) on Sendmail sisimai/set-of-emails#4