utcOffset wrong return in jest.test

**Describe the bug**
utcOffset Return number **"540"** in test

Write simple unit test for in my service, but all utc

my util
```ts
export function isBefore(_schedule: Date, _offset: number = 0): boolean {
if (!_schedule) return false;
const now = dayjs();
const schedule = dayjs(_schedule).utcOffset(_offset);
// console.log(schedule);
return schedule.isBefore(now);
}
```

```tsx
import {isBefore} from '~/utils/date';

const _isBefore = (testDate: Date, result: boolean) => {
expect(isBefore(testDate)).toBe(result);
};

describe('is_Before 테스트', () => {
it('isBefore test', () => {
const date = new Date();
_isBefore(date, true);
});
});
```

```
Console

console.log
540

at isBefore (src/utils/date.ts:44:11)

● is_Before 테스트 › isBeforeTest

TypeError: schedule.isBefore is not a function

44 | console.log(schedule);
45 | // console.log('isBefore End');
> 46 | return schedule.isBefore(now);
| ^
47 | }
48 |
49 | export function getScheduleText(_schedule: Date, _offset: number = 0): string {

at isBefore (src/utils/date.ts:46:19)
at _isBefore (__tests__/utils/date.test.ts:4:10)
at Object. (__tests__/utils/date.test.ts:10:5)
```

Real Service work correctly only problem in test

**Information**
- Day.js Version [e.g. v1.0.0]: 1.11.5
- OS: [e.g. iOS]: mac m1
- Browser [e.g. chrome 62]: node
- Time zone: [e.g. GMT-07:00 DST (Pacific Daylight Time)]: GMT-09:00

Start with src/utils/date.ts and __tests__/utils/date.test.ts, then run the failing Jest test to inspect the utcOffset result and the subsequent isBefore call. Done means the test no longer raises the reported TypeError and the date utility behavior is covered without breaking the service behavior described.

Written by the indexing model from the issue text.