      def test_default_timezone(self):
          assert self.field.default_timezone() == utc
  
      def test_current_timezone(self):
          assert self.field.default_timezone() == utc
          activate(self.kolkata)
          assert self.field.default_timezone() == self.kolkata
          deactivate()
          assert self.field.default_timezone() == utc
  
 
</s> remove         assert self.field.default_timezone() == utc
 </s> add         self.assertUTC(self.field.default_timezone()) </s> remove         assert self.field.default_timezone() == utc
 </s> add         self.assertUTC(self.field.default_timezone())
        self.assertUTC(self.field.default_timezone())
      def test_default_timezone(self):
          assert self.field.default_timezone() == utc
  
      def test_current_timezone(self):
        self.assertUTC(self.field.default_timezone())
          activate(self.kolkata)
          assert self.field.default_timezone() == self.kolkata
          deactivate()
          assert self.field.default_timezone() == utc
  
keep keep keep keep replace keep keep keep keep keep
 Fixed TestDefaultTZDateTimeField to allow multiple tzinfo implementations.

zoneinfo was made the default time zone implementation in
https://github.com/django/django/commit/306607d5b99b6eca6ae2c1e726d8eb32b9b2ca1b. 
tests/test_fields.py