Add support for serializing zoneinfo.ZoneInfo objects in migrations

[Sandeep Harlalka]

in settings.py

USE_TZ = True

In models.py

class MyClass:
     timestamp = models.DateTimeField()
    date = models.GeneratedField(
        expression=TruncDate('timestamp', tzinfo=INDIA_TIMEZONE),
        output_field=models.DateField(),
        db_persist=True,
    )

makemigrations:
ValueError: Cannot serialize: zoneinfo.ZoneInfo(key='Asia/Kolkata')

date field is added after the table has already been created.

[Sarah Boyce]

Note for others trying to replicate:

from zoneinfo import ZoneInfo

from django.db import models
from django.db.models.functions import TruncDate


INDIA_TIMEZONE = ZoneInfo('Asia/Kolkata')

class MyModel(models.Model):
    timestamp = models.DateTimeField()
    date = models.GeneratedField(
        expression=TruncDate('timestamp', tzinfo=INDIA_TIMEZONE),
        output_field=models.DateField(),
        db_persist=True,
    )

[Sarah Boyce]

As zoneinfo.ZoneInfo objects are not supported in migrations (see docs: ​https://docs.djangoproject.com/en/dev/topics/migrations/#migration-serializing), I have classed this as a new feature rather than a bug