Should we implement https://developer.mozilla.org/en-
US/docs/Web/Privacy/Privacy_sandbox/Partitioned_cookies for the session cookie?

This allows web sites to embed a tracker and keep the tracker logged in
while on the site. However, if the tracker is embedded in another site,
the user will have to log in again.

Not sure this is a use case we care about. It would make a tracker useless
for following a person from site to site, but I don't think anybody
running Roundup would want to track a user across sites.

Implementation is easy enough. In client.py find where ' secure;' is added
to the cookie and make it ' secure; partitioned;'.

If implemented I don't think it needs a config option to enable/disable. If somebody
wants to track people via Roundup they have to edit the code.

Thoughts?