Can't change a field in a copied embedded model that's part of a collection #228

[bartoszflis-silvair]

Bug

Given a model definition like this:

class E(EmbeddedModel):
    f: int

class M(Model):
    e: List[E]

model = M(e=[E(f=1)])
copy = instance.copy(deep=True)

When I call copy.e[0].f = 2
Then an AttributeError: 'E' object has no attribute '__fields_modified__' occurs

Environment

• ODMantic version: 0.9.2
• MongoDB version: 5.0.9
• Pydantic infos (output of python -c "import pydantic.utils; print(pydantic.utils.version_info())"):

            pydantic version: 1.9.1
            pydantic compiled: True
                 install path: /lib/python3.10/site-packages/pydantic
               python version: 3.10.4 (main, May  9 2022, 12:55:22) [GCC 9.3.0]
                     platform: Linux-5.4.0-73-generic-x86_64-with-glibc2.31
     optional deps. installed: ['typing-extensions']

Additional context

This is a continuation of #228 .