emulators/ucon64: Update to 2.2.1

• Add support for CD64 backup units via new default option CD64. [1]

• Update WWW field. [1]

Changelog:

https://ucon64.sourceforge.io/ucon64/changes.html

PR: 252178
Reported by: Daniël Hörchner (via e-mail) [1]
Approved by: Nicole Reid <root@cooltrainer.org> (maintainer)