Update OpenAPI, list schema and list data to support api_post_method

[MattIPv4]

With https://github.com/botblock/api-worker/pull/3 now merged, we can introduce support within the data that powers the API for the new api_post_method property.

The OpenAPI schema will need updating to indicate that lists will now return this property. It should be a nullable string.

The list schema will need updating to allow lists to define this string, again also allowing it to be nullable (and defaulting to null).

All existing lists will need to be updated to set this property to null.

[A5rocks]

All existing lists will need to be updated to set this property to null.

Just for clarification -- it can be undefined | null | string, I think. Is it be worth making it always required to remind people of it?

(I volunteer to do the necessary work once this is clarified, along with updating discordlist.gg to use PUT)

[MattIPv4]

it can be undefined | null | string

I don't think it needs to be undefined? It should be a required field in the schema like all other properties, so should just be null | string?

[A5rocks]

Probably badly phrased my question: I meant more like should it be required? Technically that would be unnecessary.

Sounds like you think it should be though, which is fine.

[MattIPv4]

Yah, all existing API fields are required but nullable, so I think this should be too.