Invalidate Core stub

In case like this on each iteration there should be created new Core stub with new data

```
it.each(validBookings)('should return valid data', async booking => {
const mocks = createSyncanoCoreMock({
endpoint: {
get: stub().resolves({inOrganization: true}),
},
user: {
findOrFail: stub().resolves({
hubUserKey: 'xyz',
}),
},
data: {
resource: {
find: resourceStub,
where: stub().fn({
firstOrFail: resourceStub,
}),
},
booking: {
fields: stub().fn({
create: bookingStub,
}),
where: stub().fn({
list: bookingWhereListStub,
}),
},
},
})

const result = await run('create', {args: booking, meta}, {mocks})
expect(result.code).toEqual(200)
})
```