Merge branch 'master' into develop

* master:
  1.12.1
  Note where bugs were introduced
  1.12.1rc1
  Newsfile
  Rewrite changelog
  Add changelog
  Only import sqlite3 when type checking
  Fix another instance
  Only setdefault for signatures if device has key_json
  Fix starting workers when federation sending not split out.
  Attempt to clarify Python version requirements (#7161)
  Improve the UX of the login fallback when using SSO (#7152)
  Update the wording of the config comment
  Lint
  Changelog
  Regenerate sample config
  Whitelist the login fallback by default for SSO