Prevent user from creating messages with wrong parameters when pydantic is used

[AdrienVannson]

Summary

Python's dataclass prevent the user from creating instances of a dataclass with invalid fields (see the test that I added). However, this is not the case by default with Pydantic: the invalid fields are just removed from the message ( https://docs.pydantic.dev/latest/api/config/#pydantic.config.ConfigDict.extra ).

This can be the cause of errors if there is a typo in the name of a parameter. For this reason, I think it is better to add config={"extra": "forbid"} to pydantic dataclasses so that a ValidationError is raised in such a situation.

To avoid adding type checking errors (this parameter does not exist in python's dataclasses), I had to remove the if TYPE_CHECKING condition that was used to import Python's dataclass instead. I updated mypy to its last versionto avoid having the bug mentionned in danielgtaylor#460 . To do this, it was needed to remove support for python 3.7... but I think it is fine given the fact that the tests are no longer run with this python version, which is very old anyway.

Checklist

• If code changes were made then they have been tested.
• This change has an associated test.