Use IO#getch to read one char in raw mode

lib/reline/ansi.rb

@@ -1,3 +1,5 @@
+require 'io/console'
+
 class Reline::ANSI
   RAW_KEYSTROKE_CONFIG = {
     [27, 91, 65] => :ed_prev_history,     # ↑
@@ -24,14 +26,7 @@ class Reline::ANSI
     unless @@buf.empty?
       return @@buf.shift
     end
-    c = nil
-    loop do
-      result = select([@@input], [], [], 0.1)
-      next if result.nil?
-      c = @@input.read(1)
-      break
-    end
-    c&.ord
+    @@input.getch&.ord
   end
 
   def self.ungetc(c)