[Carousel] Decimal value for slide-per-view prop

[weeks6]

Clear and concise description of the problem

Swiper.js allows passing decimal values e.g. "1.2" but so far naive-ui seems to support only whole numbers

Suggested solution

We could tweek necesseary calculations of translate and width to support decimal values

Alternative

No response

Additional context

No response

Validations

• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.