fix(types): defineComponent object format with no props type

[xiaoxiangmoe]

see https://github.com/vuejs/vue-next/blob/140f08991727d7c15db907eea5a101979fe390b2/packages/runtime-core/src/apiDefineComponent.ts#L95-L120

// overload 2: object format with no props
// (uses user defined props interface)
// return type is for Vetur and TSX support
export function defineComponent<
  Props = {},
  RawBindings = {},
  D = {},
  C extends ComputedOptions = {},
  M extends MethodOptions = {},
  Mixin extends ComponentOptionsMixin = ComponentOptionsMixin,
  Extends extends ComponentOptionsMixin = ComponentOptionsMixin,
  E extends EmitsOptions = EmitsOptions,
  EE extends string = string
>(
  options: ComponentOptionsWithoutProps<
    Props,
    RawBindings,
    D,
    C,
    M,
    Mixin,
    Extends,
    E,
    EE
  >
): DefineComponent<Props, RawBindings, D, C, M, Mixin, Extends, E, EE>

Vue 3 use {} rather than unknown when object format with no props.