Upgrade to pywikibot 9

[holybiber]

Pywikibot 9 is out and we're currently still using pywikibot>=8.4.0.

I found one thing in the Changelog that we need to pay attention to:

pywikibot.BaseSite and pywikibot.APISite were dropped. pywikibot.Site() has to be used to create a site object.

Not sure if there are other changes we need to take into account.

[holybiber]

We should update everything in requirements.txt to the current versions and make sure everything runs / tests pass.

[TobiasBeck777]

Ok, thanks for the hint.