Bump version requirement on PLY because of a bug in versions prior to 3.6 causing parsetab.py to be regenerated after install.
Bump version requirement on PLY because of a bug in versions prior to 3.6 causing parsetab.py to be regenerated after install.

EricssonResearch/calvin-base,KaptenJon/calvin-base,MalmoUniversity-DA366A/calvin-base,KaptenJon/calvin-base,EricssonResearch/calvin-base,les69/calvin-base,les69/calvin-base,EricssonResearch/calvin-base,MalmoUniversity-DA366A/calvin-base,EricssonResearch/calvin-base,les69/calvin-base,MalmoUniversity-DA366A/calvin-base,les69/calvin-base,KaptenJon/calvin-base