Chromium fails to load a jitsi video conference, refusing to create a
worker because it violates the Content Security Policy directive:
"script-src https: data: 'unsafe-inline' 'unsafe-eval'".
Add the `wss:` field so that Nginx does not create warning when using Websocket over TLS.
This modification only affects the `Report-Only` part of the CSP, that takes care of creating warnings in the logs.
Warning ex (fr only sorry):
```
Content Security Policy: Les paramètres de la page ont empêché le chargement d’une ressource à wss://your.website.tld (« default-src »). Un rapport CSP est en cours d’envoi.
```
