archivers/py-pyppmd: Update 1.2.0 => 1.3.1

Changelog:
https://github.com/miurahr/pyppmd/blob/v1.3.1/Changelog.rst

Commit log:
https://github.com/miurahr/pyppmd/compare/v1.2.0...v1.3.1

Add missing strip.
Fix warning from portclippy - move do-test.

PR: 291289