devel/py-setuptools_scm: Pass MAINTAINER'ship to python@

This port is required for build for a set of ports and is also quite
interlocked in terms of infrastructure. Therefore, the port should be
maintained by python@ instead of a single individual.

With hat: python@
MFH: 2023Q1

(cherry picked from commit 2b0bc5eca415d9f0522aa752c3ffe39bf05d17e0)