examples/swmr_inotify_example.py: asyncore module is deprecated and removed in Python 3.12

[drew-parsons]

h5py provides the example swmr_inotify_example.py

It uses asyncore which has been deprecated since python3.6.
Running the example warns that it will soon be removed:

$ python3 swmr_inotify_example.py 
/projects/h5py/examples/swmr_inotify_example.py:20: DeprecationWarning: The asyncore module is deprecated and will be removed in Python 3.12. The recommended replacement is asyncio
  import asyncore

Evidently asyncio should be used instead.

See also https://peps.python.org/pep-0594/#deprecated-modules

$ python3 -c 'import h5py; print(h5py.version.info)'
Summary of the h5py configuration
---------------------------------

h5py    3.9.0
HDF5    1.10.8
Python  3.11.4 (main, Jun  7 2023, 10:13:09) [GCC 12.2.0]
sys.platform    linux
sys.maxsize     9223372036854775807
numpy   1.24.2
cython (built with) 0.29.36
numpy (built against) 1.24.2
HDF5 (built against) 1.10.8

[tacaswell]

The work here is to re-write that example using modern async tools.

[takluyver]

This is further complicated because pyinotify itself seems to be dead. There are a few different inotify interfaces out there, but it looks like the cross-platform watchdog package might be the most actively maintained & widely used.