Use h5netcdf instead of netCDF4

[aidanheerdegen]

Could use h5netcdf instead of netCDF4 to write metadata attributes.

It has a new API which looks pretty sweet

import h5netcdf

with h5netcdf.File("mydata.nc", "w") as f:
    # set global attributes with simple assignment
    f.title = 'My data'
    f.institution = 'ACCESS-NRI'

It also has no dependency on the netCDF C library.