Push h5py pin back to 2.10.0

Currently ligo.em-bright requires h5py>=3.3.0, however gstlal-inspiral requires h5py<3.0.0 (see lscsoft/gstlal#62 (closed)), which means that we will not be able to deploy ligo.em-bright into the IGWN Conda Distribution, or any environment that also needs gstlal-inspiral.

Is it possible to push the h5py pin back to 2.10.0?