Missing attachments parameter from interaction callback data struct

[Stefen Sharkey]

The attachments field is missing from the discord_interaction_callback_data struct.

See https://discord.com/developers/docs/interactions/receiving-and-responding#interaction-response-object-messages

[Lucas Müller]

Thanks for letting us know, I completely missed that! I'll add that one once I have the time.

[Lucas Müller]

For future reference: https://discord.com/developers/docs/reference#uploading-files