useWatch doesn't call setState when it is object that same but not equal

[haracejacob]

reproduce

https://codesandbox.io/s/sweet-banach-t7cpoq

case 1

• If you click push button, foo is displayed in two input boxes

case 2

• First, click setFieldValue button
• Next, click push button, foo is displayed in the input box below, but not in above box.

cause

https://github.com/react-component/field-form/blob/master/src/useWatch.ts#L99

if (valueStrRef.current !== nextValueStr) {
    valueStrRef.current = nextValueStr;
    setValue(newValue);
}

it compares stringified objects. Strings are same but objects are not

I think this problem is conflicts with this issue(https://github.com/react-component/field-form/issues/431)