Make SInputSelect test coverage 100%

[kiaking]

It's not yet there.

• Current Test Coverage

For testing value and modelValue prop, we have similar test in other input components like SInputNumber.

test('it accepts `value` prop', async () => {
  const wrapper = mount(SInputNumber, {
    props: { value: 1 }
  })

  expect(getInputValue(wrapper.find('.SInputNumber .input'))).toBe('1')
})

test('it sets value to `null` when nither `value` or `modelValue` is set', async () => {
  const wrapper = mount(SInputNumber)

  expect(getInputValue(wrapper.find('.SInputNumber .input'))).toBe('')
})