Trivial: `/favicon.ico` needed

Due to the absence of `/favicon.ico`, there is a warning in the log file `/var/log/supervisor/tribe-gunicorn-stderr-*` (which was generated by `gunicorn` process):
```
Not Found: /favicon.ico
```
and `/var/log/nginx/access.log`:
```
"GET /favicon.ico HTTP/1.1" 404 261
```

Start by locating how this Python webserver serves static files and handles the /favicon.ico entry point; the issue names no source file or test. Check the request through gunicorn and nginx, then verify that /favicon.ico no longer returns 404 and the related log warnings are gone.

Written by the indexing model from the issue text.