Discord invites with `https://` prefix are considered invalid.

[lxnn]

Currently, when you try to add an invite link to the invites whitelist, it is rejected if the given link begins with https://, http://, etc.

For example:

!whitelist add guild_invite https://discord.gg/aMZJ7NAr R Programming language

This results in a BadArgument error.

Fixing this should just be a matter of adding the prefix to the regex pattern.

Relevant parts of the code:

• the regex
• the validator