How do I stop P14M converting into P1Y2M

**Not a bug but a behavior I don't want it to do**
When I dayjs.duration(14, "Month").toISOString, it returns P1Y2M

**Expected behavior**
I want P14M instead.

**Information**
- Day.js Version V1.11.5
- OS: Windows 10
- Browser: Chrome

The issue names dayjs.duration(...).toISOString as the entry point. Investigate how that call converts a 14-month duration, then verify that the result is P14M instead of P1Y2M.

Written by the indexing model from the issue text.