Add sphinx to setup.py

[kozo2]

This will fix the following ModuleNotFoundError

import py4cytoscape as p4c

ModuleNotFoundError                       Traceback (most recent call last)
<ipython-input-2-c772b26fd5a4> in <module>
----> 1 import py4cytoscape as p4c

~\miniforge3\lib\site-packages\py4cytoscape\__init__.py in <module>
     20 """
     21 
---> 22 from .networks import *
     23 from .session import *
     24 from .layouts import *

~\miniforge3\lib\site-packages\py4cytoscape\networks.py in <module>
     50 from . import network_selection
     51 from . import layouts
---> 52 from . import session
     53 from . import sandbox
     54 

~\miniforge3\lib\site-packages\py4cytoscape\session.py in <module>
     24 # Internal module imports
     25 from . import commands
---> 26 from . import sandbox
     27 
     28 # Internal module convenience imports

~\miniforge3\lib\site-packages\py4cytoscape\sandbox.py in <module>
     24         `Sandboxing <https://py4cytoscape.readthedocs.io/en/latest/concepts.html#sandboxing>`_ in the Concepts section in the py4cytoscape User Manual.
     25 """
---> 26 from sphinx.addnodes import desc
     27 
     28 """Note that there is more detailed commentary and lower level functions in py4cytsocape_sandbox.py."""

ModuleNotFoundError: No module named 'sphinx'

[bdemchak]

@kozo2 I'm tentatively rejecting this for 0.0.9. I see that this import was added to 0.0.9/sandbox.py here, but I don't see the reason for it, and I don't see what breaks if I remove the import. So, without the import, there's no need for the PR. Do you see it differently?

[kozo2]

Now I checked the same in the HEAD of the 0.0.9 branch, the ModuleNotFoundError did not appear. You can ignore this issue.