getPrecision always returns 0 when step size value is an integer

When the value for the step size is an integer, the function getPrecision (https://github.com/react-component/slider/blob/9.2.4/src/utils.js#L35) always returns a precision of 0, which is not desired. There should be a way to pass the precision of a step to allow a situation as the following:

const sliderProps = {
  value: 5.5,
  step: 3,
  min: 2.5,
  max: 20.5
};

In the situation above, the handle won't take a value lower than 3 with the current implementation in v9.2.4. Although the closest point of 2.5 is found when dragging the handle, the ensureValuePrecision function (https://github.com/react-component/slider/blob/9.2.4/src/utils.js#L69) will round it off to an integer (3 in this case).

Start in src/utils.js at getPrecision and ensureValuePrecision, then trace how the step size and minimum value reach those helpers. Verify the reported case with value 5.5, step 3, min 2.5, and max 20.5; done means the slider can retain the valid minimum of 2.5 instead of rounding it to 3.