fix: lazy import ArrayField to avoid requiring psycopg2

[zkksdk]

Fix for Issue #100

Problem

django_seed/guessers.py unconditionally imports ArrayField from django.contrib.postgres.fields, which requires the psycopg2 package even when the project is not using PostgreSQL as its database. This causes ModuleNotFoundError: No module named 'psycopg2' when running seed.py on projects using SQLite or MySQL.

Root Cause

from django.contrib.postgres.fields import ArrayField  # requires psycopg2

Fix

Use try/except ImportError (same pattern already used for JSONField in this file), and guard the isinstance check for when ArrayField is unavailable:

try:
    from django.contrib.postgres.fields import ArrayField
except ImportError:
    ArrayField = None

And in the isinstance check:

if ArrayField and isinstance(field, ArrayField):

Testing

Run seed.py on a Django project that does NOT have psycopg2 installed and does NOT use PostgreSQL. Previously this failed with ModuleNotFoundError. Now it works.

Fixes #100