Bump streamlit-webrtc from 0.20.1 to 0.21.0

Bumps [streamlit-webrtc](https://github.com/whitphx/streamlit-webrtc) from 0.20.1 to 0.21.0.
- [Release notes](https://github.com/whitphx/streamlit-webrtc/releases)
- [Changelog](https://github.com/whitphx/streamlit-webrtc/blob/main/CHANGELOG.md)
- [Commits](https://github.com/whitphx/streamlit-webrtc/compare/v0.20.1...v0.21.0)

---
updated-dependencies:
- dependency-name: streamlit-webrtc
dependency-type: direct:production
update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

requirements.txt

@@ -5,5 +5,5 @@ numpy==1.20.3
 opencv_python==4.5.2.54
 pydub==0.25.1
 streamlit==0.82.0
-streamlit_webrtc==0.20.1
+streamlit_webrtc==0.21.0
 typing_extensions==3.10.0.0