tests/test_HDF5_recorder.py: Add `__setitem__` tests for current group.
tests/test_HDF5_recorder.py: Add `__setitem__` tests for current group.

jakirkham/nanshe,nanshe-org/nanshe,DudLab/nanshe,jakirkham/nanshe,DudLab/nanshe,nanshe-org/nanshe