isort 5.0.0 dropped support for Python 3.5.

ENT-3073

This will allow for more controlled releases of enterprise code in edx-platform.

This change will prevent Library Content from being marked as
complete on view and the corresponding version bump to
edx-completion contains code that will start looking at the
children of the library content for completeness.

...and pin django-ipware for the moment

Removing ddt constraint.

The new releases end up importing code in Studio that relies on an LMS-only setting. Pinning until resolved.

Also pinning edx-completion until the test failures in #24365 get resolved.

Upgrade to 1.0.0 caused issues which are described and being
investigated in https://github.com/django-ses/django-ses/issues/186.

Upgrade transifex-client version.

This is only made in order to run the tests with a transifex-client version compatible with python3.8

The actual problem that we have in edx-platform is that the last version of transifex-client has as constraint python-slugify<2.0.0 which is not compatible with the current requierements of edx-platform on the other hand, the current version used in edx-platform is not compatible with python3.8

sympy needs to be at a newer version for python3.

updated the constraints order

Remove pandas requirement.
Replace pandas functionality with itertools.group_by.

* Updating Python Requirements

* Pin django-pipeline and lxml

Co-authored-by: Jeremy Bowman <jbowman@edx.org>

Cleaned up a few more things about the testing configuration now that we've deployed Django 2.2 to production:

* Go back to a single version of django-oauth-toolkit, tox doesn't need to vary it anymore
* Go back to PyPI release of django-method-override
* Remove no longer needed dependency on python-oauth2 (we already removed the package it was used by)
* Update prepare_xdist_nodes.sh with new Django requirements file options

This reverts commit 27480a25.

* Updating Python Requirements

* Constrain django-cookies-samesite until dep bug fixed

* Fix PEP 8 problems revealed by pycodestyle upgrade

Co-authored-by: Tim McCormack <tmccormack@edx.org>
Co-authored-by: Jeremy Bowman <jbowman@edx.org>

Constrain ddt<1.4.0 until this issue is fixed:
- https://github.com/datadriventests/ddt/issues/83

These were pinned because they drop support for Django<2.2 (or were
planning on it, in the latter case.)

No related changes in computed requirements.

See ARCHBOM-1141 for details.  Effort required to upgrade pip.

ARCHBOM-1141:

This adds contraints to:
kiwisolver: next release only works with python>=3.6

The was run to upgrade:
django-splash
django-wiki
edx-search
The previous versions were constraining django below 2.0.

Co-authored-by: Robert Raposa <rraposa@edx.org>

We'll upgrade this again along with pytest once pytest-dev/pytest#6925 is resolved.

Also, it looks like a flaky error in test class DB setup outside a transaction was mucking things up for the rest of the test shard. I didn't try to fix the flakiness, but this should at least limit the blast radius to just that test class. We really need to start using setUpTestData() more consistently.

Also pinned httpretty < 1.0 because that upgrade broke many tests.

-Upgrade edx-drf-extensions
-settings-update