Update backbone files and code base to address new ObsPy release (1.3.0)
- Remove constraints on NumPy version. New ObsPy release (1.3.0) fixes import error with latest NumPy release (1.22)
- Update obspy_replace modules based on fixes implemented in new ObsPy (1.3.0). Check issue #2678 in ObsPy GitHub page for more details on PASSCAL suggested updates to the obspy.io.reftek library.
- Remove support for Python 3.6
- Add support for Python 3.9
- Update CI/CD file to allow for measuring code coverage of modules.