Heads up: Python 3.9 removes tp_print: will need some requirements to be updated to newer releases

Just a heads up. Python 3.9 removes `tp_print`:

https://docs.python.org/release/3.9.0/whatsnew/3.9.html#id3

While installing NetPyNE-UI using `pip install -r requirements.txt` on the development branch, this will make the build fail because a few of the deps are frozen at older versions that do not include fixes for Python 3.9. On my test run, wheels failed to build for these because of this particular error:

- pandas,
- ruamel-yaml

The rest were fine. Had a scipy issue too, but seems to be a different compilation error.