Bugfix release for netCDF4>=1.7.0

[pp-mo]

The #84 changes adapted an assumption in our tests of the dtypes available, just to check we are testing all the relevant ones.
What actually changed was the introduction of complex dtypes in netCDF4, from v1.7.0 onward
(included from about 2023-12-8), released about 2024-07-13
-- NOT anying to do with numpy, which has had them since at least v1.13

So we could make a bugfix release, since at present an up-to-date env with latest ncdata is failing tests.

NOTE: afaik this only affects tests, not the main module functions. Since the failure is in the test support code

[pp-mo]

Long gone now, I think