adding model card link direct in app.py

Same as was done in https://huggingface.co/spaces/CVPR/ml-talking-face/commit/e28a921859dfb71c94b6ee8392d1cce36d57fc4e, but diff than instructed in https://discuss.huggingface.co/t/how-to-link-the-spaces-with-arxiv/27094/4 and done for spurious demo, as a sanity check.

app.py

@@ -1,3 +1,4 @@
+# Model card: https://huggingface.co/emilylearning/selection-induced-collider-bias
 # %%
 import gradio as gr
 import matplotlib.pyplot as plt