django foreignkey(user) in models

Don't use the User model directly.

From the documentation

Instead of referring to User directly, you should reference the user model using django.contrib.auth.get_user_model()

When you define a foreign key or many-to-many relations to the user model, you should specify the custom model using the AUTH_USER_MODEL setting.

Example:

from django.conf import settings
from django.db import models

class Article(models.Model):
    author = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        on_delete=models.CASCADE,
    )

If you created a custom User model, you would use setting.AUTH_USER_MODEL, if not you can go ahead an use User model

Referencing Django User model