Merge branch 'master' into glitch-soc/merge-upstream

Merge branch 'master' into glitch-soc/merge-upstream

Conflicts:
- app/javascript/mastodon/features/compose/components/compose_form.js
  Upstream cleaned up a bit, including on lines in which
  we replaced the hardcoded 500 character limit with a maxChar
  constant. Applied the changes while keeping maxChar instead of 500.
- app/javascript/packs/public.js
  Moved upstream's new animated avatar hover handling in
  app/javascript/core/public.js
- app/javascript/styles/fonts/montserrat.scss
  Upstream fixed local font name, applied those changes.
- app/javascript/styles/fonts/roboto.scss
  Upstream fixed local font name, applied those changes.
- lib/mastodon/version.rb
  Upstream made repo URL configurable, did the same, but
  default to glitch-soc