update jquery.ui.datepicker-de.js (#13825)

This is from following revision.
https://github.com/jquery/jquery-ui/commit/10ca48308fea6a9b30d2457fbf5a1b6e0ed5966c

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@11735 e93f8b46-1217-0410-a6f0-8f06a7374b81