Make `dehumanize()` handle values with decimal fractions correctly

Feature Request

Currently, dehumanize() is not capable of correctly parsing values with a floating point.

>>> arrow.get("2025-12-10T09:00:00").dehumanize("2 days 3.5 hours ago")
<Arrow [2025-12-08T04:00:00+00:00]>

It seems that parser pretty much ignores the part up to the floating point.

A more expected result, however, would be that resulting Arrow object is <Arrow [2025-12-08T05:30:00+00:00]>

Not sure if there is a need to make floating point locale-dependent (ie, . or ,), perhaps it'd be fine to allow both.