[BUG] Beanie persists root field

[WingCode]

Describe the bug
Beanie persists root field in the database when using Pydantic RootModel. The root field must not be persisted in the database.

To Reproduce

from typing import List
from motor.motor_asyncio import AsyncIOMotorClient
from pydantic import RootModel
from beanie import Document, init_beanie

Pets = RootModel[List[str]]

class PetDocument(Document):
    content: Pets

async def example():
    client = AsyncIOMotorClient("mongodb://user:pass@host:27017")

    await init_beanie(database=client.db_name, document_models=[PetDocument])

    my_pets = PetDocument(content=["dog", "cat", "fish"])

    await my_pets.insert()

import asyncio
asyncio.run(example())

Expected behavior
In MongoDB it is expected to have record like

{"content": ["dog", "cat", "fish"]

but instead it stores it as

{"content": {"root":["dog", "cat", "fish"]}}

[roman-right]

Hi! Let me check this Pydantic feature and the doc.

[roman-right]

Fixed in #669 . Please, try

[WingCode]

This has been fixed in #669 . Thank you for looking into it!