Initiating Recalls_mt with num_classes = 6 by default

[jfltzngr]

Environment info

• bikit version: 0.0.11
• Platform: --
• Used Versions: --

Information

In Class Recalls_mt(Recall):
We shouldn't initiate num_classes inside def __init__(self, average='none', num_classes=6) with 6 (Only valid for CODEBRIM).
Otherwise, users might have difficulties when being confronted with the Error that num_classes don't match the input.

To reproduce

--

Expected behavior

assert if num_classes is given.