Fix zensus weather cell mapping

[nailend]

Fixes #1031.

Before merging into dev-branch, please make sure that

• [x] the CHANGELOG.rst was updated.
• [x] new and adjusted code is formated using black and isort.
• [x] the Dataset-version is updated when existing datasets are adjusted.
• [x] the branch was merged into the continuous-integration/run-everything-over-the-weekend-branch.
• [x] the workflow is running successful in test mode.
• [x] the workflow is running successful in Everything mode.

[nailend]

In my current run everything worked and the changes look good :+1:

Great, was a DE run, wasn't it?

[khelfen]

In my current run everything worked and the changes look good +1

Great, was a DE run, wasn't it?

Unfortunately no. I can't get a DE run to work atm (failing at zensus.zensus-misc-to-postgres now :roll_eyes: )

[nesnoj]

Can this be merged?

[nesnoj]

At least it ran successfully on the Flensburg server. But I did not check any results.