TST/CI: Skip batched comm test win / tornado5 (#4166)
TST/CI: Skip batched comm test win / tornado5 (#4166)

Previously we only skipped on Python 3.6. Now we skip on any Python
version on Windows with Tornado 5.

I can reproduce the issue if people want me to look more, but I don't
think this is high priority.

Closes https://github.com/dask/distributed/issues/4163.
dask/distributed,dask/distributed,dask/distributed,dask/distributed