Inconsistent _prev type: sets vs tuples

[Terminay]

_create_child converts prev to a tuple (line 44), but several methods pass {self} (a set) instead of (self,) (a tuple).
This works by accident but is inconsistent:
exp, log, sigmoid, softmax, relu, tanh, leaky_relu, and gelu all use sets, while __add__, __sub__, __mul__, __truediv__, __pow__, __matmul__, and __neg__ use tuples.

[github-actions]

The issue raises a concern about inconsistent use of types for the prev parameter in a _create_child function, where it is converted to a tuple, but some methods pass a set ({self}) instead of a tuple ((self,)). This inconsistency occurs across various mathematical and activation functions, with some using sets and others using tuples, even though the code works despite this mismatch.