Duration from ISO String with milliseconds doesn't set milliseconds

**Describe the bug**
Creating a duration from an ISO String doesn't set the milliseconds in the duration object.
`dayjs.duration("P4DT12H30M17.899S")`
returns
`{ years: 0, months: 0, weeks: 0, days: 4, hours: 12, minutes: 30, seconds: 17.899 }`

**Expected behavior**
The milliseconds will be set
`{ years: 0, months: 0, weeks: 0, days: 4, hours: 12, minutes: 30, seconds: 17, milliseconds: 899 }`

**Information**
- Day.js Version v1.10.7

Start by running the reported dayjs.duration("P4DT12H30M17.899S") expression and trace the duration parsing entry point. Confirm that the resulting object separates seconds from milliseconds as shown in the expected behavior, then verify the same case with the project's relevant tests.

Written by the indexing model from the issue text.