weekOfYear week method doesn't seems to handle week number 53 for 'de-at' locale

**Describe the bug**
I have an issue with the dayjs week() method compared with the moment.js one.
My issue is probably linked to this one https://github.com/iamkun/dayjs/issues/956

**Expected behavior**
I tried with that date: 2020-12-31, which is supposed to be a day in the week number 53. (if i refer to this http://www.whatweekisit.org/). But it returns week number as 1

**Information**
- Day.js Version [e.g. v1.11.20]
- OS: [Mac OS]
- Browser [Chrome 147]
- Time zone: [Central European Summer Time]

Start by reproducing the week() result for 2020-12-31 with the de-at locale and compare it with Moment.js. Read the related issue #956 for context, then trace the weekOfYear behavior for locale-specific week numbering. Done means the date returns week 53 for de-at and the behavior is covered by a regression test.

Written by the indexing model from the issue text.