Fixed some flake8 errors.

Originally I added migrations to flake8 exclude because of long lines
in migration files, but there are other directories named migrations we
do want to check. We are not warning on line lengths yet anyway.
Made a GIS test work on Oracle.

Thanks Josh Smeaton and Claude Paroz for advice.
Skipped a broken GIS test on Oracle; refs #23504.
Don't recommend using sudo when installing uwsgi
Merge pull request #3244 from mattrobenolt/patch-5

Don't recommend using sudo when installing uwsgi
Small fixes in templates topic guide.

>>> from django.template.defaultfilters import register
>>> len(register.filters)
57
Fixed #23530 -- Specified PyYAML requirement in initial-data.txt

Thanks aks for the report.
Fixed #23196 -- Short-circuited empty string translation

Translating an empty string used to return the gettext catalog
metadata instead of the empty string.
Thanks Ned Batchelder for the suggestion, Tim Graham for the review
and Anton Berezin and Claude Paroz for contributions to the patch.
Fixed an i18n test with native string

Refs commit 11f307a5a8.
Fixed #23529 -- Replaced comments tag library with humanize in docs
Fixed #23527 -- Removed Cheetah references in docs

Thanks to @aaugustin for submitting the ticket.
Fixed #23512 -- Made migration docs about initial_data clearer

Thanks @abhillman and @Markush2010 for submitting the ticket.