*: compatibility with DateTime >= 3 🚧

drop the patch in DateTime._parse_args which cause DateTime to
support timezone naive dates

adjust __setstate__ to pickle the timezone naive flag

adjust code relying on DateTime private attributes

adjust tests for new DateTime.__eq__ behavior (instances with
different timezones are different)

more testing, especially for various __setstate__ versions

introduce a context manager to change timezone in tests.
4 jobs for feat/datetime3 in 0 seconds
Status Job ID Name Coverage
  External
failed ERP5.CodingStyleTest-TestRunner2

05:39:10

failed ERP5.UnitTest-TestRunner2

08:39:34

failed ERP5.CodingStyleTest-TestRunner2

01:02:47

passed ERP5.UnitTest-TestRunner2

01:59:26