Bump pyScss version to fix local dev

[ajyong]

I was following DEVELOPMENT.md and using the Vagrant route but ran into a pip install error:

Collecting psycopg2==2.8.4
  Using cached psycopg2-2.8.4.tar.gz (377 kB)
Collecting pyScss==1.3.5
  Using cached pyScss-1.3.5.tar.gz (123 kB)
    ERROR: Command errored out with exit status 1:
     command: /gavel/env/bin/python -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/tmp/pip-install-d3yyy60h/pyScss/setup.py'"'"'; __file__='"'"'/tmp/pip-install-d3yyy60h/pyScss/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' egg_info --egg-base /tmp/pip-install-d3yyy60h/pyScss/pip-egg-info
         cwd: /tmp/pip-install-d3yyy60h/pyScss/
    Complete output (5 lines):
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/tmp/pip-install-d3yyy60h/pyScss/setup.py", line 9, in <module>
        from setuptools import setup, Extension, Feature
    ImportError: cannot import name 'Feature' from 'setuptools' (/gavel/env/lib/python3.7/site-packages/setuptools/__init__.py)
    ----------------------------------------
ERROR: Command errored out with exit status 1: python setup.py egg_info Check the logs for full command output.

Apparently this was an intended change by PyPA, but I don't understand why they did not clean up their __init__.py.

Because downgrading the setuptools given to me by virtualenv felt wrong, I opted to instead bump pyScss up two minor versions from 1.3.5 to 1.3.7.

I think this is including a commit you made in master that doesn't exist in develop. Let me know if I'm PRing into the right branch. Thank you!

[anishathalye]

Merged in 9f4454c. Thank you!