Fixed the error and added smooth function to optimate the clusters

[Starlitnightly]

Added the smooth fuction:

adata_bin60.obs['louvain_smooth']=st.tl.smooth(adata_bin60, radius=5, key='louvain')
st.pl.space(adata_bin60, color=['louvain_smooth'], show_legend="upper left", 
            figsize=(4, 3), color_key_cmap="tab20")

adata_bin60.obs['scc_smooth']=st.tl.smooth(adata_bin60, radius=5, key='scc')
st.pl.space(adata_bin60, color=['scc_smooth'], show_legend="upper left", 
            figsize=(4, 3), color_key_cmap="tab20")

Fixed the cluster_method key error in function scc

This is an interesting error report, when I started trying to reproduce scc's tutorial it prompted me that the cluster_method parameter was unavailable, upon checking I found that leiden was hardcoded in the spateo code, I re-added the parameter in a new pull request and re-added the louvain related methods.

Pr: aristoteleo/spateo-release#250