Update Litestar asgi template

[sinisaos]

PiccoloORMPlugin is no longer used in Litestar 2. A new feature is PiccoloDTO (not released yet) which I tried and works well but I found some limitations. For example Interval column does not work because timedelta is not currently supported in msgspec. I would simply update the Litestar asgi template with create_pydantic_model (which we also use in other templates) because that way everything will work well and we will be much less dependent on changes in Litestar (we could unpin dependencies from Litestar==2.0.0a3 to the latest version). With create_pydantic_model we can easily solve the problem with Interval column because we can add custom type encoder and pass it to app constructor like this

TYPE_ENCODERS = {datetime.timedelta: str}

app = Litestar(
   route_handlers=[],
   type_encoders=TYPE_ENCODERS,
)

That change does not work in PiccoloDTO due to a serialization error. @dantownsend What do you think about that, would that be a smart thing to do? If yes, I can make those changes.

[dantownsend]

@sinisaos Your suggested changes make sense. We can get the litestar template working again without having to version pin it, and then if msgspec supports timedelta in the future, and PiccoloDTO is released, we can switch over to using PiccoloDTO.