type: onChange callback should define 'option' as Option | Option[] |…

… undefined (#1090)

src/Select.tsx

@@ -161,7 +161,7 @@ export interface SelectProps<ValueType = any, OptionType extends BaseOptionType
   value?: ValueType | null;
   defaultValue?: ValueType | null;
   maxCount?: number;
-  onChange?: (value: ValueType, option: OptionType | OptionType[]) => void;
+  onChange?: (value: ValueType, option?: OptionType | OptionType[]) => void;
 }
 
 function isRawValue(value: DraftValueType): value is RawValueType {