* py-petsc4py: Update version to 3.8.0 and add dependencies
- Added explicit dependency on python and numpy
* Kept old version - and corrected minimal python version
* Update to 3.8.1
* Add installer for petsc4py and slepc4py
* @adamjstewart requested changes on this pull request; make these type=('build', 'run')
* @citibeth suggestion Remove unneeded indirect dependencies