Please try the latest release of streamlit-webrtc (0.44.1) that I just published 
This problem and its solution were reported at AttributeError: 'builtins.Certificate' object has no attribute '_x509' · Issue #1164 · whitphx/streamlit-webrtc · GitHub, then I published a new version of streamlit-webrtc with the fix.
It looks like the recently released version of cryptography, 0.39.0 (cryptography · PyPI) causes this problem, and it is discussed at Certificate error when creating RTCDtlsTransport with Cryptography 39.0.0 · Issue #804 · aiortc/aiortc · GitHub