www/py-freenit: Update to 0.1.15

Changelog[1]:

• Improve project initialization

[1] https://github.com/freenit-framework/backend/releases/tag/0.1.15

PR: 250230
Submitted by: Goran Mekic <meka@tilda.center> (maintainer)
Approved by: tcberner (mentor)
Differential Revision: https://reviews.freebsd.org/D26732