Bump uvicorn from 0.7.0 to 0.11.7 in /examples/server/asgi

Bumps [uvicorn](https://github.com/encode/uvicorn) from 0.7.0 to 0.11.7.
- [Release notes](https://github.com/encode/uvicorn/releases)
- [Changelog](https://github.com/encode/uvicorn/blob/master/CHANGELOG.md)
- [Commits](https://github.com/encode/uvicorn/compare/0.7.0...0.11.7)

Signed-off-by: dependabot[bot] <support@github.com>

examples/server/asgi/requirements.txt

@@ -4,6 +4,6 @@ httptools==0.0.13
 python-engineio
 python_socketio
 six==1.11.0
-uvicorn==0.7.0
+uvicorn==0.11.7
 uvloop==0.12.2
 websockets==7.0