[cleanup] Fix some flake8 errors and drop upper bound of copyright along the way. autoform module is not added to flake8-ok-files since there are some remaining errors to be handled, but that's still a start.

Release notes
-------------

.. toctree::
    :maxdepth: 1

    3.25
    3.24
    3.23
    3.22
    3.21
    3.20
    3.19
    3.18
    3.17
    3.16
    3.15
    3.14