Tool calling: support more types

[aymeric-roucher]

What does this PR do?

Adds more supported types in chat templates.
Why not use an empty type for "any"?
=> Sometimes users want to specify a type hint like this:

def get_weather(location: Any) -> None:
    return "Nice weather today."

=> In that case, I think it makes it more explicit to have the type hint being precised in the json schema as "any" rather than left empty as is currently the case.

I don't know if these changes are compatible with the current usage of chat template in transformers (in particular, maybe some models are trained with the convention to let the type for 'Any' blank), but they allow finer definition of inputs which is useful for using transformers chat templates in smolagents. Let me know if this is an appropriate change @Rocketknight1!

[CISC]

any is not part of the JSON Schema specification, so I think this should be left unset.

However setting NoneType to null is the right thing to do and seems to have been an omission.

@Rocketknight1 I noticed some of your chat templates are missing the handling of null as well, and as I've reused your json_to_python_type macro I added this in f.ex. MiniCPM-4B and Dria-Agent models' templates.

[Rocketknight1]

Seconding @CISC's comment, I don't think we can use {"type": "any"}, but the type for None is definitely appreciated!

[aymeric-roucher]

That's updated @Rocketknight1 ! Thanks to you and @CISC for your feedback! 🤗

[Rocketknight1]

LGTM!