Deserialization of float8_e5m2

I tried the following code snippet, and it doesn't seem to work. Is this an already known issue?

```
>>> a = float8_e5m2(1.5)
>>> np.save("a.npy", a)
>>> b = np.load("a.npy")
Traceback (most recent call last):
File "/home/wonjeo01/.local/lib/python3.10/site-packages/numpy/lib/format.py", line 640, in _read_array_header
dtype = descr_to_dtype(d['descr'])
File "/home/wonjeo01/.local/lib/python3.10/site-packages/numpy/lib/format.py", line 309, in descr_to_dtype
return numpy.dtype(descr)
TypeError: data type '", line 1, in
File "/home/wonjeo01/.local/lib/python3.10/site-packages/numpy/lib/npyio.py", line 432, in load
return format.read_array(fid, allow_pickle=allow_pickle,
File "/home/wonjeo01/.local/lib/python3.10/site-packages/numpy/lib/format.py", line 765, in read_array
shape, fortran_order, dtype = _read_array_header(
File "/home/wonjeo01/.local/lib/python3.10/site-packages/numpy/lib/format.py", line 643, in _read_array_header
raise ValueError(msg.format(d['descr'])) from e
ValueError: descr is not a valid dtype descriptor: '