Ensure primitives are type-cast for encode

[atyshka]

This ensures primitive-inheriting types are cast to primitives, resolving issue #48

[dlwh]

any chance i could get you add a unit test actually?

[atyshka]

I'm glad you asked for that, I caught a bug with enums. The encoded string gets the class prefix, which didn't work for the existing decoding logic. I implemented a fix for this in the decoding. I think it would be cleaner if we could encode it without the prefix, that is, using the enum encoder rather than the string encoder, but I'm unsure how that should be implemented.

Although it's worth noting the messiness of this could be solved by StrEnum in python 3.11+, but draccus needs some solution for 3.9/3.10

[atyshka]

I guess we could just do something like this:

def encode_string(x, _=None):
    if isinstance(x, Enum):
        return encode_enum(x)
    else:
        return str(x)
encode.register(t, encode_string, include_subclasses=True)

Let me know which solution you prefer or if you have alternative suggestions

[dlwh]

enums are special enough to deserve a special case, but we could lift it up to where e.g. is_dataclass is.

it's also probably time to drop 3.9 (which is a few weeks away from EOL). 3.10 i'm not committed to supporting really but probably not quite time to drop it.