Update Tor Browser User Agent for 8.0
Update Tor Browser User Agent for 8.0

Tor Browser's user agent now contains platform/OS due to changes in
upstream Firefox (see https://trac.torproject.org/projects/tor/ticket/26146).
We should explicitly list all platforms (instead of relaxing the regex to avoid matching `Android; Mobile`, Orfox's UA string.

Platform list obtained from: https://gitweb.torproject.org/boklm/tor-browser-bundle-testsuite.git/commit/?id=e27a9843e9d928438e15ca5885577d3b7eb0551a

ehartsuyker/securedrop,heartsucker/securedrop,conorsch/securedrop,heartsucker/securedrop,heartsucker/securedrop,ehartsuyker/securedrop,heartsucker/securedrop,conorsch/securedrop,conorsch/securedrop,ehartsuyker/securedrop,ehartsuyker/securedrop,heartsucker/securedrop,ehartsuyker/securedrop,ehartsuyker/securedrop,conorsch/securedrop,conorsch/securedrop