Update python for build docs to python 3.12

[Czaki]

🧰 Task

We should update python for build docs to at least python 3.12 (to have a year or two without next maintenance job).

This requires to change Qt backend used from build docs, as python 3.10 is the latest supported by pyside2 from pypi.

We either plan to drop pyside2, so we need to update workflow from this reason. I suggest two PRs:

• change backend used for build docs
• bump python for docs to at least 3.12

[psobolewskiPhD]

the GitHub build_deploy has been using pyqt5:

docs/.github/workflows/build_and_deploy.yml

Line 62 in 0c066aa

python -m pip install "napari/[all]"

In #590 i make circleCI also use pyqt5