Function avg_pool2d 

pub fn avg_pool2d<B>(
    x: Tensor<B, 4>,
    kernel_size: [usize; 2],
    stride: [usize; 2],
    padding: [usize; 2],
    count_include_pad: bool,
) -> Tensor<B, 4>
where
    B: Backend,

Applies a 2D avg pooling.