www/seahub: Updated to 6.1.5

[ultima]

Summary

• Updated to 6.1.5

Reviewed by\: lifanov (mentor), matthew (mentor)
Approved by\: lifanov (mentor), matthew (mentor)
Differential Revision\: https://reviews.freebsd.org/DXXXXX

Test Plan

portlint:
www/py-seafdav
WARN: Makefile: for new port, make $FreeBSD$ tag in comment section empty, to make SVN happy.
0 fatal errors and 1 warning found.
www/py-seafobj
WARN: Makefile: for new port, make $FreeBSD$ tag in comment section empty, to make SVN happy.
0 fatal errors and 1 warning found.
www/seahub
WARN: Makefile: [0]: possible direct use of command "file" found. use ${FILE} instead.
WARN: Makefile: for new port, make $FreeBSD$ tag in comment section empty, to make SVN happy.
0 fatal errors and 2 warnings found.
poudriere:
103i386
103amd64
110i386
110amd64
12i386
12amd64

[lifanov]

Mention all affected ports in the commit message.
Otherwise, this looks OK!