Update Disnake to support Forum Channels

[Micha-ohne-el]

Also fixes missing column in database insert. Not sure why this wasn't caught earlier.

Updates Disnake to 2.6.0 (latest version as of this PR).

[Run1e]

Thanks for the PR, I will try it and merge it when I get on my workstation again.

The reason for the missing database column insert is that there's a mismatch between my manual changes to the live database and migrate.sql. The completed field is supposed to have a default value of FALSE but I just forgot to add that to migrate.sql.

The changes done to the sql query can be undone and migrate.sql fixed instead.

[onerandomusername]

just fyi, disnake 2.7.0 will be released tomorrow, along with 2.6.2