Pager: use TerminalInfo API for `::page_size`

Fix issue #829 (NoMethodError: undefined method `winsize'
for #<IO:<STDOUT>>, The Same Error as #549 But On The Latest Version
(0.9.11.4))

lib/pry/pager.rb

@@ -24,12 +24,8 @@ class Pry::Pager
   end
 
   def self.page_size
-    @page_size ||= begin
-      require 'io/console'
-      $stdout.winsize.first
-    rescue LoadError
-      27
-    end
+    rows = Pry::TerminalInfo.screen_size
+    @page_size ||= (rows && rows.first || 27)
   end
 
   def initialize(text)