[Bug Report] Box2d car racing environment fails to take integer action

[brseong]

Describe the bug

8161d7d#diff-b2657ab36b5d46d0f112f0c7d20e3026e4d50c8a0e260e5669002d229e5f027cR544

the newly added line 543 of box2d/car_racing.py always fails to run non-continuous action.

Code example

Replacing the type casting may be helpful:

#line 540
def step(self, action: Union[np.ndarray, int]):
    assert self.car is not None
        if action is not None:
            if self.continuous:
                action = action.astype(np.float64)
                self.car.steer(-action[0])
                self.car.gas(action[1])
                self.car.brake(action[2])
            else:
                if not self.action_space.contains(action):
                    raise InvalidAction(
                        f"you passed the invalid action `{action}`. "
                        f"The supported action_space is `{self.action_space}`"
                    )
                self.car.steer(-0.6 * (action == 1) + 0.6 * (action == 2))
                self.car.gas(0.2 * (action == 3))
                self.car.brake(0.8 * (action == 4))

System info

No response

Additional context

No response

Checklist

• I have checked that there is no similar issue in the repo

[pseudo-rnd-thoughts]

Could you make a PR fixing this along with a test about it?