Fix type annotations examples

[DanieleMorotti]

I fixed the type annotations errors for pydantic objects in some examples as noted in #490 .

When running make lint the following error occurs "UP007 Use X | Y for type annotations". If you know how to ignore it I will be happy to edit the pull request, thanks.

[rm-openai]

Actually you can just do from __future__ import annotations and these type errors will go away on 3.9

[DanieleMorotti]

Yes, I thought that was the solution, but it doesn't work when using | within a pydantic BaseModel class, maybe due to how Pydantic works.

For example, I got the following error:

TypeError: Unable to evaluate type annotation 'str | None'. If you are making use of the new typing syntax (unions using `|` since Python 3.10 or builtins subscripting since Python 3.9), you should either replace the use of new syntax with the existing `typing` constructs or install the `eval_type_backport` package.

Let me know if I'm wrong and I have to change the pull request.

[rm-openai]

cool - can you fix lint please?

[rm-openai]

oh wait lint is complaining about the exact thing i talked about hmm

[rm-openai]

I think you can do what it says and add https://pypi.org/project/eval-type-backport/, based on pydantic/pydantic#7873

[DanieleMorotti]

I added the library to the dependencies as suggested, it should work now, tests passed