text: Title: icdf of beta distribution is not implemented
  Body: ```python
  >>> import numpyro.distributions as dist
  >>> d = dist.Beta(1, 5)
  >>> d.icdf(0.975)
  Traceback (most recent call last):
    File "<stdin>", line 1, in <module>
    File "/home/ayaka/venv/lib/python3.10/site-packages/numpyro/distributions/distribution.py", line 463, in icdf
      raise NotImplementedError
  NotImplementedError
  ```
  
  NumPyro version: 0.9.1