fix(VRating): allow string model-value

[jacekkarczmarczyk]

Description

Changed modelValue prop type from number to string|number

Alternatively examples in docs could be changed from model-value="3" to :model-value="3"

How Has This Been Tested?

playground

Markup:

<template>
  <div>
    <v-rating model-value="3" />
  </div>
  <div>
    num: {{ num }} {{ JSON.stringify(num) }}
  </div>
  <div>
    <v-rating v-model="num" half-increments />
  </div>
  <div>
    str: {{ str }} {{ JSON.stringify(str) }}
  </div>
  <div>
    <v-rating v-model="str" half-increments />
  </div>
</template>

<script setup>
  import { ref } from 'vue'
  const num = ref(3)
  const str = ref('3.5')
</script>

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Improvement/refactoring (non-breaking change that doesn't add any features but makes things better)

Checklist:

• The PR title is no longer than 64 characters.
• The PR is submitted to the correct branch (master for bug fixes and documentation updates, dev for new features and backwards compatible changes and next for non-backwards compatible changes).
• My code follows the code style of this project.
• I've added relevant changes to the documentation (applies to new features and breaking changes in core library)