BXR ChannelGroup reading causes error with h5py>=3.0.0

[Helveg]

Reading an item from the ChannelGroup dataset /3BUserInfo/ChsGroups with h5py>=3.0.0 causes:

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ERROR: test_channel_group_names (test_file.TestChannelGroups)
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Traceback (most recent call last):
  File "/mnt/c/Users/robin/Documents/GIT/bwpy/tests/test_file.py", line 61, in test_channel_group_names
    names = f.get_channel_group_names()
  File "/mnt/c/Users/robin/Documents/GIT/bwpy/bwpy/__init__.py", line 76, in get_channel_group_names
    print("GROUP0", self.get_raw_user_info()["ChsGroups"][()])
  File "h5py/_objects.pyx", line 54, in h5py._objects.with_phil.wrapper
  File "h5py/_objects.pyx", line 55, in h5py._objects.with_phil.wrapper
  File "/home/robin/.pyenv/versions/3.8.6/lib/python3.8/site-packages/h5py/_hl/dataset.py", line 784, in __getitem__
    self.id.read(mspace, fspace, arr, mtype, dxpl=self._dxpl)
  File "h5py/_objects.pyx", line 54, in h5py._objects.with_phil.wrapper
  File "h5py/_objects.pyx", line 55, in h5py._objects.with_phil.wrapper
  File "h5py/h5d.pyx", line 192, in h5py.h5d.DatasetID.read
  File "h5py/_proxy.pyx", line 141, in h5py._proxy.dset_rw
  File "h5py/_conv.pyx", line 670, in h5py._conv.vlen2ndarray
  File "h5py/_conv.pyx", line 717, in h5py._conv.conv_vlen2ndarray
ValueError: data type must provide an itemsize

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