[ruby/reline] correct Win32API capitalization for JRuby

JRuby 9.4.0.0 introduced a change in case sensitivity in require statements,
meaning that an inclusion of `win32api` loaded Win32API.rb. With this change,
the require statement needs to be updated to the correct capitalization of the
filename to avoid reline failures in newer versions of JRuby.

https://github.com/ruby/reline/commit/d6e7c9e1d9

lib/reline/windows.rb

@@ -53,7 +53,7 @@ class Reline::Windows
   end
 
   if defined? JRUBY_VERSION
-    require 'win32api'
+    require 'Win32API'
   else
     class Win32API
       DLL = {}