numpy 2 compatibility in the iris code paths (pydata#9156)

* don't remove `cf_units` (and thus `iris`) [skip-ci]

* try keeping netcdf4, h5netcdf, and h5py

Author: keewis

ci/install-upstream-wheels.sh

@@ -13,7 +13,7 @@ $conda remove -y numba numbagg sparse
 # temporarily remove numexpr
 $conda remove -y numexpr
 # temporarily remove backends
-$conda remove -y cf_units pydap
+$conda remove -y pydap
 # forcibly remove packages to avoid artifacts
 $conda remove -y --force \
     numpy \