fix: Setup should be ephemeral

[sudojunior]

Minor fix, content needs to be included with the message payload. Instead of implying it as a string argument case.

slash-create method docs

https://github.com/TinkerStorm/interaction-prototypes/blob/232ff467bb4ad6c4a11c45c3db7bfeca2437182f/src/commands/setup.ts#L79