py-tables: updated to 3.6.1

Changes from 3.6.0 to 3.6.1
Maintenance release to fix packaging issues. No new features or bugfixes.

Changes from 3.5.3 to 3.6.0
PyTables 3.6 no longer supports Python 2.7.

Improvements
- Full python 3.8 support.
- On Windows PyTables wheels on PyPI are linked to `pytables_hdf5.dll` instead of
`hdf5.dll` to prevent collisions with other packages/wheels that also vendor `hdf5.dll`.
This should prevent problems that arise when a different version of a dll is imported
that the version to which the program was linked to. This problem is known as "DLL Hell".
With the renaming of the HDF5 DLL to `pytables_hdf5.dll` these problems should be solved.

Bugfixes
- Bugfix for HDF5 files/types with padding. For details see :issue:`734`.
- More fixes for python 3.8 compatibility: Replace deprecated time.clock
  with time.perf_counter
- Improvements in tests as well as clean up from dropping Python 2.7 support.

(adam)