Revert "[ruby/io-console] Skip cursor position test on Solaris"

This reverts commit 5294ded681.

test/io/console/test_io_console.rb

@@ -285,7 +285,6 @@ defined?(PTY) and defined?(IO.console) and TestIO_Console.class_eval do
   end
 
   def test_cursor_position
-    skip if /solaris/ =~ RUBY_PLATFORM
     run_pty("#{<<~"begin;"}\n#{<<~'end;'}") do |r, w, _|
       begin;
         con = IO.console