Aleph-message and sdk now uses pydantic v2 but no released yet
Using the github link atm and wait for the release.

When upgrading the pydantic version, some function are / will become
deprecated. replacing them in those files.

Added `default=extended_json_encoder` to `json.dumps()` to handle serialization
of non-native JSON types, such as dates and other complex objects.

Replacing function that are / will be deprecated in pydantic v2 and v3

Pydantic>=2 is not compatible with fastapi<0.100.0

Conflit between pydantic and yamlfix
black did not pass

With Pydantic v2, strict type validation is enforced. The type field is expected
to have the exact value "POST" as a literal.