net/gemserv: Update to 0.6.6

ChangeLog: https://git.sr.ht/~int80h/gemserv/tree/v0.6.6/item/README#L79

This update fixes a security issue for which there is no CVE assigned:

https://git.sr.ht/~int80h/gemserv/refs

PR: 265800
Reported by: contact@evilham.com
Approved by: ea@uoga.net (maintainer)