www/adguardhome: Fix build

adguardhome has a dependency which does not support go 1.18 yet. Use
1.17 for now.

PR: 262994
Reported by: Yonas Yanfa <yonas.yanfa@gmail.com>
Approved by: portmgr (implicit, build fix)

(cherry picked from commit 5d3b802e93dadb51f686dfbad65ba2475d44fc1a)