Reading https:// netCDF files does not work

[davidhassell]

At version 1.10.1.1, reading a https:// files does not work, but reading an http:// file does work:

>>> import cfdm
>>> remote = "http://psl.noaa.gov/thredds/dodsC/Datasets/cru/crutem5/Monthlies/air.mon.anom.nobs.nc"
>>> cfdm.read(remote)
[<Field: air_temperature_anomaly(time(2082), latitude(36), longitude(72)) observations>]
>>> remote = "https://psl.noaa.gov/thredds/dodsC/Datasets/cru/crutem5/Monthlies/air.mon.anom.nobs.nc"
>>> cfdm.read(remote)
--------------------------------------------------------------------------
OSError                                   Traceback (most recent call last)
Cell In[3], line 1
----> 1 f = cfdm.read(remote)

File ~/cfdm/cfdm/read_write/read.py:360, in read(filename, external, extra, verbose, warnings, warn_valid, mask, domain, _implementation)
    355     raise IOError(
    356         f"Can't determine format of file {filename} "
    357         f"generated from CDL file {cdl_filename}"
    358     )
    359 else:
--> 360     raise IOError(f"Can't determine format of file {filename}")
    362 # ----------------------------------------------------------------
    363 # Return the field or domain constructs
    364 # ----------------------------------------------------------------
    365 return fields

OSError: Can't determine format of file https://psl.noaa.gov/thredds/dodsC/Datasets/cru/crutem5/Monthlies/air.mon.anom.nobs.nc

This is due to a simple bug in cfdm.read_write.netcdf.netcdfread.is_netcdf_file. PR to follow.