multimedia/py-soco: Update to 0.18.1

• Add a "do-test" target to make future QA easier while I'm here.

Changelog:

https://github.com/SoCo/SoCo/releases/tag/v0.18
https://github.com/SoCo/SoCo/compare/v0.18...v0.18.1

PR: 241345
Submitted by: Conall O'Brien <conall@conall.net> (maintainer)