upgrade to onion v3

[mrphs]

With the support of onion v3 landing in stable Tor, it is time to take advantage of the better crypto and security properties of next generation of onion. I'm not sure what's the best way to coordinate the effort with all the maintainers of the servers included on the static map, but it would be great to nudge them to upgrade to onion v3 if they haven't already. And also to include the ones who already have. I know Riseup has, for example.

[taggart]

There are still quite a few v2 addresses in the map.yml but I don't know how many are valid. Maybe another reason to switch to SRV and stop maintaining this by hand?