Reuse of `genePT_w_emebed` where `genePT_s_emebed` should be used

[jeremyadamsfisher]

In block 36 of aorta_data_analysis.ipynb, it seems that genePT_s_emebed is not used and genePT_w_emebed is re-used inappropriately

# Split the data into training and test sets (80/20)
genePT_s_emebed = sampled_cell_aorta_gpt[np.where(sampled_adata.obs.celltype!='Unknown')[0]]
y_celltype_remove_unknown = sampled_adata.obs.celltype[np.where(sampled_adata.obs.celltype!='Unknown')[0]]
#                                                                               vvvvvvvvvvvvvvv
genePT_s_emebed_train, genePT_s_emebed_test, y_train, y_test = train_test_split(genePT_w_emebed, 
                                                    y_celltype_remove_unknown,
                                                    test_size=0.20, random_state=2023)

It seems this code wasn't actually run, because the notebook fails unless I substitute genePT_w_emebed with genePT_s_emebed.