ALEPH-126 - Upgrade pydantic version

[RezaRahemtola]

The current version of pydantic used is <2.0.0, while the 2.0 has been out for more than a year now (in fact we are at v2.9.1 atm).

This means that for newly created projects, installing pydantic then aleph-sdk-python (that depends on aleph-message) throws an error and forces the user to downgrade their pydantic version, which might be problematic (not in this specific case for me, but at LibertAI we have our agents framework that requires features of pydantic v2, so people won't be able to use it with the aleph-sdk)

[RezaRahemtola]

cc @philogicae @hoh

[hoh]

The main motivation for staying on pydantic 1 was that it was the version packaged on Debian stabe.

I believe that given the additional constraints we have now, aleph-message should either be made compatible with both versions or aleph-vm should vendor pydantic 2.