Handle interrupts directly at io/console

Added to io/console at commit at 24, September, 2019
* ruby/io-console@7cba765

Released in Ruby 2.7.0, released at 25, December, 2019
* https://www.ruby-lang.org/en/news/2019/12/25/ruby-2-7-0-released/

Documented at 17, February, 2020
* ruby/io-console@82b630c

Documented in Ruby 2.7.1, released at 31, March, 2020
* https://ruby-doc.org/stdlib-2.7.1/libdoc/io/console/rdoc/IO.html#method-i-getch
* https://www.ruby-lang.org/en/news/2020/03/31/ruby-2-7-1-released/

lib/highline/terminal/io_console.rb

@@ -27,7 +27,7 @@ def restore_mode
 
       # (see Terminal#get_character)
       def get_character
-        input.getch # from ruby io/console
+        input.getch(intr: true) # from ruby io/console
       rescue Errno::ENOTTY
         input.getc
       end