Use Python's builtin isinstance() instead of this

[Aareon]

https://github.com/Devoxin/Lavalink.py/blob/c16ad73e2b1f3a471d1917714869c701c293af96/utils/Utils.py#L11

Rather than creating an all new function for something that is already built in to Python, maybe we should use isinstance()

[Aareon]

isinstance(num, int)

returns True or False

[devoxin]

Fixed in 24c09e7