String generation fails on Django 4.2 for CharField(max_length=None)

[knyghty]

Describe the issue
CharField can have max_length=None when using Postgres and Django 4.2+. model bakery isn't aware of this and will try to generate a string of length None. I suggest we add a check if max_length is None and if so, we just use a static range of 100 chars or so.

To Reproduce
Try to generate a string when using CharField() with no max_length on Postgres.

Expected behavior
I get some kind of string returned.

Versions

• Python: 3.11
• Django 4.2
• Model Bakery 1.11.0