Correct Discord Invite Regex

[mbaruh]

The current invite regex is too permissive. It captures any non-space character, while invite codes can only have letters and numbers.

bot-core/botcore/utils/regex.py

Line 15 in 127d0ef

r"(?P<invite>\S+)", # the invite code itself

In c9daa6f we made it go until the whitespace because of the way the Discord client parses invites, but we can safely account for it by adding / to the character class instead (i.e [a-zA-Z0-9/-]).

[mbaruh]

Sooo apparently there are other characters to account for here. The only thing that I can say atm is that a ? stops the invite code parsing.