 to use for timesteps. Choose from positional or fourier.
time_embedding_dim (int, optional, defaults to None):
An optional override for the dimension of the projected time embedding.
time_embedding_act_fn (str, optional, defaults to None):
Optional activation function to use only once on the time embeddings before they are passed to the rest of
the UNet. Choose from silu, mish, gelu, and swish.
timestep_post_act (str, optional, defaults to Non