🇬🇧 Updated to v3.1.3.

(Previous announcement contains an error, we were running v3.0.1 then v3.0.2 (security fix).)

Changelogs:

3.1.3: https://github.com/tootsuite/mastodon/releases/tag/v3.1.3
3.1.2: https://github.com/tootsuite/mastodon/releases/tag/v3.1.2
3.1.0: https://github.com/tootsuite/mastodon/releases/tag/v3.1.0