Fix python3 imports in lalapps_string_final
Description
This MR fixes some ModuleNotFoundErrors on python3 related to renamed standard library modules.
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.
Review Status
Please provide details on any reviews related to this change and and the associated reviewers.