maint(precommit): Apply isort (#3195)

* Apply isort

* Tweak isort config

* Add env.py as a known_first_party

* Add one missing known first party

* Make config compat with older isort versions

* Add another comment

* Revert pyproject setting

tests/extra_setuptools/test_setuphelper.py

@@ -1,7 +1,7 @@
 # -*- coding: utf-8 -*-
 import os
-import sys
 import subprocess
+import sys
 from textwrap import dedent
 
 import pytest