Can't get real-time data from FormState.

### Are you submitting a **bug report** or a **feature request**?
bug report

### What is the current behavior?
According to[ your document](https://final-form.org/docs/final-form/types/FormState#values), `FormState.values` is the current values of the form. However, when the form data is changed, `FormState` doesn't renew it's values in **real-time**. The only way to get the changed data is `subscribe` the values. I don't know why I can't get current data with `FormState.values`.

### What is the expected behavior?
Just like what document says, if the input is changed, `FormState.values` should be changed, too.

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### What's your environment?

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