relativeTime outputs wrong amount of months

**Describe the bug**
When you put in custom thresholds for relativeTime to output everything up to 9999 months as months, and enter a duration longer than 36 months, some months get lost.

**Expected behavior**
Output of correct amount of month

**Information**
- dayjs 1.9.3
- Windows
- Chrome
- CEST

I created a fiddle here https://jsfiddle.net/sy50xg2e/1/

**Details**
```
const config = {
thresholds: [
{l: 's', r: 59, d: 'second'},
{l: 'm', r: 59},
{l: 'mm', r: 59, d: 'minute'},
{l: 'h', r: 23},
{l: 'hh', r: 23, d: 'hour'},
{l: 'd', r: 29},
{l: 'dd', r: 29, d: 'day'},
{l: 'M', r: 1},
{l: 'MM', r: 9999, d: 'month'}
// {l: 'y', r: 1},
// {l: 'yy', r: 9999, d: 'year'}
]

};

dayjs.extend(dayjs_plugin_relativeTime, config)
dayjs.extend(dayjs_plugin_duration)

console.log(dayjs.duration(36, "month").humanize());
console.log(dayjs.duration(37, "month").humanize());
console.log(dayjs.duration(38, "month").humanize());
console.log(dayjs.duration(9999, "month").humanize());
```

The output is:
```
"36 months"
"36 months"
"37 months"
"9855 months"
```

I'd expect, 36, 37, 38, 9999.

Start with the relativeTime and duration plugins and reproduce the issue using the provided JSFiddle configuration and duration examples. Verify that humanize() preserves the correct month counts for 36, 37, 38, and 9999 months; done means the outputs match the expected values without breaking the existing thresholds.

Written by the indexing model from the issue text.