simulateHeterodynedCW.py: remove explicit ephem name check
HeterodynedCWSimulator it sets the solar system ephemeris type, e.g., DE200 or DE405. Currently, when this gets set it checks whether the value is one of 4 values. This hardcoding can be problematic if you want to use a different ephemeris. This MR removes that check. There are still checks that will catch if an ephemeris file doesn't exist.
API Changes and Justification
Backwards Compatible Changes
- This change introduces no API changes
- This change adds new API calls
Backwards Incompatible Changes
- This change modifies an existing API
- This change removes an existing API
If any of the Backwards Incompatible check boxes are ticked please provide a justification why this change is necessary and why it needs to be done in a backwards incompatible way.