Drop python 2 / pylint 2.0 remnants

[Pierre-Sassoulas]

pylint-django is not compatible with pylint 2 nor python 2 anymore since some time ago, but some compat layers are still there and have a run time impact as well as a maintenance impact.

Better reviewed commit by commit.

[coveralls]

Pull Request Test Coverage Report for Build 19209516980

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-85.3%) to 0.0%

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Totals
Change from base Build 19209151625:	-85.3%
Covered Lines:	0
Relevant Lines:	0

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💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 19210045568

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-85.3%) to 0.0%

---

Totals
Change from base Build 19209151625:	-85.3%
Covered Lines:	0
Relevant Lines:	0

---

💛 - Coveralls