daysInMonth() returns 1 when timezone is Asia/Kuala_Lumpur

**Describe the bug**
dayjs('1981-12-01').daysInMonth() returns 1 when browser's timezone is set to either:
- Asia/Kuala_Lumpur
- Asia/Singapore

On January 1, 1982, both Malaysia (where Kuala Lumpur is the capital city) and Singapore adjusted their time zones forward by 30 minutes, moving from UTC+07:30 to UTC+08:00. daysInMonth() could not handle this change of time offset and returns incorrect result.

**Expected behavior**
dayjs('1981-12-01').daysInMonth() should return 31.

**Information**
- Day.js Version v1.10.6
- OS: Windows
- Browser: Chrome, Firefox
- Time zone: Asia/Kuala_Lumpur and Asia/Singapore (UTC+8:00)