devel/py-python-dbusmock: update to 0.34.1

While here, prefer DISTVERSION over PORTVERSION.

Changelog:

• https://github.com/martinpitt/python-dbusmock/releases/tag/0.33.0
• https://github.com/martinpitt/python-dbusmock/releases/tag/0.34.0
• https://github.com/martinpitt/python-dbusmock/releases/tag/0.34.1

Reported by: Repology