Fixes class disambiguation logic when there is nested inheritance

[aasiffaizal]

Fixes the case mentioned here in #117

Below is the example pointed out by @slafs

# -- bar.py
from package.foo import Foo

class Bar(Foo):
    b: str

# -- foo.py
from pydantic import BaseModel

class Foo(BaseModel):
    a: str

# -- baz.py
from package.bar import Bar

class Baz(Bar):
    c: str

At the end class visits we are left with CLS_CONTEXT_KEY being

{'package.bar.Bar': {'package.baz.Baz'}}

Instead of just disambiguating at one level over here

bump-pydantic/bump_pydantic/codemods/class_def_visitor.py

Lines 61 to 85 in dda0b55

	# In case we have the following scenario:
	# class A(B): ...
	# class B(BaseModel): ...
	# class D(C): ...
	# class C: ...
	# We want to disambiguate `A` as soon as we see `B` is a `BaseModel`.
	if (
	fqn.name in self.context.scratch[self.BASE_MODEL_CONTEXT_KEY]
	and fqn.name in self.context.scratch[self.CLS_CONTEXT_KEY]
	):
	for parent_class in self.context.scratch[self.CLS_CONTEXT_KEY].pop(fqn.name):
	self.context.scratch[self.BASE_MODEL_CONTEXT_KEY].add(parent_class)
	# In case we have the following scenario:
	# class A(B): ...
	# class B(BaseModel): ...
	# class D(C): ...
	# class C: ...
	# We want to disambiguate `D` as soon as we see `C` is NOT a `BaseModel`.
	if (
	fqn.name in self.context.scratch[self.NO_BASE_MODEL_CONTEXT_KEY]
	and fqn.name in self.context.scratch[self.CLS_CONTEXT_KEY]
	):
	for parent_class in self.context.scratch[self.CLS_CONTEXT_KEY].pop(fqn.name):
	self.context.scratch[self.NO_BASE_MODEL_CONTEXT_KEY].add(parent_class)

I have changed the logic to recursively disambiguate its children as well.

I noticed that ClassDefVisitor unittest is fully commented out so I added an integration test for it. Happy to add the unittest if required.