Fix Registration's Bug

[Thoughtseize1]

As a user, I would like to register on our service without having to provide a profile picture URL. Currently, when attempting to register without a profile picture URL, an error occurs:

Request URL: http://127.0.0.1:8000/api/users/register/
IntegrityError: NOT NULL constraint failed: users.profile_img_url

Steps to Reproduce: Send a POST request to /api/users/register/ with the following data (without profile_img_url field):

{
    "email": "Nikita@ukr.net",
    "password": "YGGFY2%%",
    "password2": "YGGFY2%%",
    "first_name": "Nikita",
    "last_name": "Sherstianykh"
}

Expected Behavior: Users should be able to register successfully without providing a profile picture URL.

Task Requirements:

• Update the registration process to allow registration without a profile picture URL.
• Ensure the profile_img_url field is optional during registration.
• Validate that users can register successfully without providing a profile picture URL.

Please fix this issue.