Instance updated to v2.8.4

Changelog:
v2.8.3: https://github.com/tootsuite/mastodon/releases/tag/v2.8.3
✴️ Improved OpenGraph tags
✴️ Improved web UI

v2.8.4: https://github.com/tootsuite/mastodon/releases/tag/v2.8.4
✴️ Improved security of the streaming API
✴️ Several fixes

#mastodon #update