Mastodon 4 requires running pre- and post-deployment migrations, something like

```
abra app run your.app.domain app bash -c "SKIP_POST_DEPLOYMENT_MIGRATIONS=true rails db:migrate"
abra app restart your.app.domain app
abra app restart your.app.domain streaming
abra app restart your.app.domain sidekiq
abra app run your.app.domain app rails db:migrate
```

See the full release notes for details: https://github.com/mastodon/mastodon/releases/tag/v4.0.0