While perusing through Glitch's PRs, I came across the patch from Chuckya
that lifts this restriction[0].
The patch exposes this restriction has been lifted with an extra flag in
the /api/v1/instance endpoint. Since Iceshrimp.NET does not have such a
restriction, signal the same flag so clients can adjust themselves
accordingly.
Clients don't seem to be aware of this flag just yet so this likely
won't have any immediate effects.
[0]: https://github.com/glitch-soc/mastodon/pull/2524
