tune.uniform upper bound included

When sampling from `tune.uniform(0, 1)`, I got a 1. According to its [docstring](https://github.com/microsoft/FLAML/blob/7f9402b8fd64f25e8f95d342fefc8eea1c006f2a/flaml/tune/sample.py#L535), uniform is supposed to behave like `numpy.random.uniform`. According to the latest [docs](https://numpy.org/doc/stable/reference/random/generated/numpy.random.uniform.html) of the `numpy`, however, `high` should be excluded.