Adding Gaussian Error Linear Unit to neural network activation functions

[ParamThakkar123]

What would you like to share?

I would like to contribute the Gaussian Error Linear Unit (GELU) activation function file in this repository under the neural network activation functions folder.

Additional information

No response

[tianyizheng02]

We already have an implementation of the GELU function in maths/gaussian_error_linear_unit.py. I'm aware that the file should be placed in the neural_networks/activation_functions directory, but we don't want duplicate implementations of a single algorithm. Please consider moving the existing file instead of contributing your own implementation.