Fix warnings about the Config class being deprecated in Pydantic 3

[samn]

Also upgrades a couple of dev dependencies needed to get the build running.

Fixes the following warning that Pydantic v2 issues used with this library:

PydanticDeprecatedSince20: Support for class-based `config` is deprecated, use ConfigDict instead. Deprecated in Pydantic V2.0 to be removed in V3.0. See Pydantic V2 Migration Guide at https://errors.pydantic.dev/2.11/migration/
    warnings.warn(DEPRECATION_MESSAGE, DeprecationWarning)

[samn]

Ran a little test in the repl to show that this works:

>>> class A:
...     if True:
...             a_field = 1
...     else:
...             class SubClass:
...                     b_field = 2
... 
>>> A().a_field
1
>>> A().b_field
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'A' object has no attribute 'b_field'. Did you mean: 'a_field'?
>>> class A:
...     if False:
...             a_field = 1
...     else:
...             class SubClass:
...                     b_field = 2
... 
>>> A().a_field
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'A' object has no attribute 'a_field'
>>> A().SubClass
<class '__main__.A.SubClass'>
>>> A().SubClass().b_field
2

[samn]

@microsoft-github-policy-service agree [company="Upstream Tech"]

[samn]

@microsoft-github-policy-service agree company="Upstream Tech"

[ghidalgo3]

Thank you!