fix(VMenu): fix min width

[lzl0304]

Description

fixes #16987

Markup:

<template>
  <v-container>
    <div class="text-center">
      <v-menu>
        <template v-slot:activator="{ props }">
          <v-btn v-bind="props">
            Auto width
          </v-btn>
        </template>
        <v-list>
          <v-list-item>
            <v-list-item-title>Here</v-list-item-title>
          </v-list-item>
        </v-list>
      </v-menu>
      <v-menu min-width="500">
        <template v-slot:activator="{ props }">
          <v-btn v-bind="props">
            Min width
          </v-btn>
        </template>
        <v-list>
          <v-list-item>
            <v-list-item-title>Here</v-list-item-title>
          </v-list-item>
        </v-list>
      </v-menu>
    </div>
  </v-container>
</template>