Fix linter warnings

Author: djhi

packages/ra-core/src/form/useInput.stories.tsx

@@ -1,5 +1,4 @@
 import * as React from 'react';
-import { useForm, FormProvider, useFieldArray } from 'react-hook-form';
 import { CoreAdminContext } from '../core';
 import { Form } from './Form';
 import { InputProps, useInput } from './useInput';