set correct testpaths for pytest

[mjoerg]

Changelog: Fix: Set correct testpaths for pytest.
Docs: Omit

The tests were moved to a new location in c6748b1.
This updates pytest's testpaths to the new path, and also corrects the documentation accordingly.

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[AbrilRBS]

Wow, nice catch! Thanks a lot for taking the time to correct the issue, we appreciate it :)