obs table initialized with incorrect types

[taldcroft]

Starting from a supplement that has no pre-existing obs dataset:

(ska3) ➜  agasc git:(update-script-fixes) python agasc/scripts/update_obs_status.py --obs 46686 --agasc-id=175379112 --status=bad --comments="ACA high background event"
INFO:agasc.supplement:updating "obs" table in agasc_supplement.h5
INFO:agasc.supplement:Appending agasc_id='175379112', obsid='46686', status={'ok': 0, 'comments': 'ACA high background event'}
(ska3) ➜  agasc git:(update-script-fixes) ipython
Python 3.8.3 (default, Jul  2 2020, 11:26:31) 
Type 'copyright', 'credits' or 'license' for more information
IPython 7.16.1 -- An enhanced Interactive Python. Type '?' for help.

In [1]: astro                                                                                                                                      
astropy=4.0.1.post1

In [2]: t = Table.read('agasc_supplement.h5', path='obs')                                                                                          

In [3]: t                                                                                                                                          
Out[3]: 
<Table length=1>
obsid   agasc_id   ok            comments        
bytes5   bytes9  uint64          bytes25         
------ --------- ------ -------------------------
 46686 175379112      0 ACA high background event