multimedia/py-mat2: update to 0.13.2

A bug fix release, addressing a crash with some Python versions.

Changelog: https://0xacab.org/jvoisin/mat2/-/blob/master/CHANGELOG.md

PR: 269225
MFH: 2023Q1
Approved by: flo (mentor)
Differential Revision: https://reviews.freebsd.org/D38513