Fix import statement for netcdf_file in calcam.py

[munechika-koyo]

Summary

This is the change to the netcdf_file import statement due to the following warning message from scipy:

.pixi/envs/test/lib/python3.14/site-packages/cherab/tools/observers/calcam.py:21
  /Users/koyo/Documents/cherab/imas/.pixi/envs/test/lib/python3.14/site-packages/cherab/tools/observers/calcam.py:21: DeprecationWarning: Please import `netcdf_file` from the `scipy.io` namespace; the `scipy.io.netcdf` namespace is deprecated and will be removed in SciPy 2.0.0.
    from scipy.io.netcdf import netcdf_file

[Mateasek]

Thanks for this @munechika-koyo

[Mateasek]

I realised, could you update changelog please?

[munechika-koyo]

I realised, could you update changelog please?

Sure! I updated it.

[Mateasek]

thanks @Mateasek, Ill merge this into development.