Toml and maybe even yaml support

[samuelcolvin]

Google suggestions makes me think toml parsing support would be very popular, we might as well also do yaml, it shouldn't be much more work.

We should use the builtin toml parser when possible, and have optional dependency groups.

[Smixi]

Hello,

Learning pydantic and pydantic settings.
I'm not used to work with optionnal dependencies. I used the same mecanism in pydantic with email-validator.
If the current code is OK for you I will add TOML,
I basically copied the docs example from Jsonsource (which I added too).
The builtin tomlib is only available from python 3.11, but the project is >=3.8.

=3.11 = tomlib
<3.11 = fallback toml reader lib.

Do you have any recommandation for the tomlib you want me to use ?

Note: pyyaml seems broken on 3.12 with Cython :'(

[kjithin]

Hello,

We should be able to create Toml & Yaml source by inheriting InitSettingsSource. Toml and Yaml parsing libraries generates a dict which the InitSettingsSource also uses to configure the source. I added the toml source for reference.

Is there any downside to inheriting from InitSettingsSource?

[Smixi]

@kjithin I update the PR, I guess it's better to use the base class you mentionned :).

Is there a specific technique to handle module import during test, so the coverage will be happy :D ?

[hramezani]

Added in #211