Merge tag 'v4.2.1' into tedomum

.rubocop_todo.yml

CHANGELOG.md

Gemfile.lock

SECURITY.md

app/controllers/concerns/web_app_controller_concern.rb

app/controllers/follower_accounts_controller.rb

app/controllers/following_accounts_controller.rb

app/helpers/database_helper.rb

app/javascript/mastodon/actions/search.js

app/javascript/mastodon/components/__tests__/hashtag_bar.tsx

app/javascript/mastodon/components/admin/Retention.jsx

app/javascript/mastodon/components/column.jsx

app/javascript/mastodon/components/hashtag_bar.tsx

app/javascript/mastodon/components/scrollable_list.jsx

app/javascript/mastodon/features/explore/index.jsx

app/javascript/mastodon/features/explore/links.jsx

app/javascript/mastodon/features/explore/results.jsx

app/javascript/mastodon/features/explore/suggestions.jsx

app/javascript/mastodon/features/explore/tags.jsx

app/javascript/mastodon/features/firehose/index.jsx