Fix $assert must be of type Inertia\Testing\Assert

[SamuelMwangiW]

Fix Argument #1 ($assert) must be of type Inertia\Testing\Assert, Inertia\Testing\AssertableInertia given error in tests

[SamuelMwangiW]

It would be much better to make it in this way: use Inertia\Testing\AssertableInertia as Assert

Thanks @Leotrimlota for your review. I have update the class to a alias instead. I personally would have preferred the Class name in full but I agree to be wrong.