gnu: python-django: Update to 3.1.1.

gnu: python-django: Update to 3.1.1.

* gnu/packages/django.scm (python-django): Update to 3.1.1.
[arguments]: Remove #:modules.  Rename set-tzdir phase to pre-check, and
disable one test.  Adjust PYTHONPATH patching to preserve all entries.  Ensure
the test suite runs sequentially.
[propagated-inputs]: Add PYTHON-ASGIREF.
(python-django-2.2): New public variable.
* gnu/packages/mail.scm (python-hyperkitty)[propagated-inptus]: Change from
PYTHON-DJANGO to PYTHON-DJANGO-2.2.
* gnu/packages/patchutils.scm (patchwork)[propagated-inputs]: Likewise.