I could not find it either back in the days, when I wanted to suppress it, but my suspicion is that is linked to some not-so-up-to-date portions of the code (the code is based on a repo that used Streamlit 1.34, I believe). Nevertheless, what I did in my personal projects was suppressing all the warnings with:
from warnings import filterwarnings
filterwarnings(action="ignore")
# source -> https://www.geeksforgeeks.org/how-to-disable-python-warnings/
Hope this helps!