v0.14.0

Added

• UnsetType is now part of the public API (re-exported from
  rest_framework_services). It is the type of the UNSET sentinel, exported
  so callers can annotate sentinel-defaulted fields cleanly —
  bio: str | None | UnsetType = UNSET — instead of suppressing the
  type-checker with # type: ignore[assignment]. The class was previously
  private (_Unset); it has been renamed and promoted (the old name was never
  exported, so this is not a breaking change).