fix: revert automatic two way sync of v-model prop values

[nekosaur]

reverts changes made in #393. two way syncing can be done using the following code

const wrapper = mount(component, {
  props: {
    modelValue: 1,
    'onUpdate:modelValue': async (modelValue: number) => await wrapper.setProps({ modelValue })
  }
})

discussion regarding potential additional mount option for v-model usage continues in #279

closes #440

[lmiller1990]

Thanks! I'll think about v-model a little more but won't delay the next release of this too much.