Thanks for getting back to me, @Maria 
I was able to fork your repo and successfully deploy to Streamlit Sharing after adding libsndfile1-dev to packages.txt. The contents of the file are exactly the following:
python3.7-venv
freeglut3-dev
libgtk2.0-dev
libasound2-dev
libsndfile1-dev
ffmpeg
Could try making the 
change and re-booting your app?
The app should look like this once you reboot it:
Happy Streamlit-ing!
Snehan