net-mgmt/unifi6: Update to 6.5.54

This is a security release, fixing a vulnerability in an embedded
log4j library.

Release notes: https://community.ui.com/releases/r/network/6.5.54

Security: CVE-2021-44228
MFH: 2021Q4
(cherry picked from commit 4fa85ecd3e9748bf6f6ceb0d7a9d62b9c71461bb)