Use week year

Fix #9463

components/date-picker/WeekPicker.tsx

@@ -11,7 +11,7 @@ function formatValue(value: moment.Moment | null, format: string): string {
 
 export default class WeekPicker extends React.Component<any, any> {
   static defaultProps = {
-    format: 'YYYY-wo',
+    format: 'gggg-wo',
     allowClear: true,
   };
 

components/date-picker/index.tsx

@@ -14,7 +14,7 @@ const MonthPicker = wrapPicker(createPicker(MonthCalendar), 'YYYY-MM');
 Object.assign(DatePicker, {
   RangePicker: wrapPicker(RangePicker),
   MonthPicker,
-  WeekPicker: wrapPicker(WeekPicker, 'YYYY-wo'),
+  WeekPicker: wrapPicker(WeekPicker, 'gggg-wo'),
 });
 
 export default DatePicker as DatePickerDecorator;