Twitter rate limit handling

[themarolt]

Changes proposed ✍️

• Twitter API rate limit handling
• Small refactor of slack rate limit handling so that we don't repeat the common code
• fixed formatting in PR GitHub template

Checklist ✅

• Label appropriately with Feature, Enhancement, or Bug.
• Tests are passing.
• New backend functionality has been unit-tested.
• Environment variables have been updated:
  • Local frontend configuration: frontend/.env.dist.local, frontend/.env.dist.composed.
  • Local backend: backend/.env.dist.local, backend/.env.dist.composed.
  • Configuration docs have been updated.
  • Team members only: update environment variables in override, staging and production env. files and trigger update config script.
• API documentation has been updated (if necessary) (see [docs on API documentation](https://docs.crowd.dev/docs/updating-api-documentation)).
• Quality standards are met.
• All changes have been tested in a staging site.
• All changes are working locally running crowd.dev's Docker local environment.