Update python versions for tox.ini to be same as github actions

[vjf]

Overview

Update python versions in tox.ini to be same as the python versions in github actions

Related Issue / Discussion

Additional Information

Contributions and Licensing

(as per https://github.com/geopython/pycsw/blob/master/CONTRIBUTING.rst#contributions-and-licensing)

• I'd like to contribute update python versions in tox.ini to pycsw. I confirm that my contributions to pycsw will be compatible with the pycsw license guidelines at the time of contribution.
• I have already previously agreed to the pycsw Contributions and Licensing Guidelines