Have version number be modifyable in one place, used everywhere needed

[OpenDataAlex]

Currently there are four spots that have to be updated:

• mysql_process_tracker_defaults.sql
• postgresql_process_tracker_defaults.sql
• process_tracker.init.py
• setup.py
  Would be nice to be able to call it from one place and update accordingly.

[OpenDataAlex]

Setup.py gets version from process_tracker.init.py. The sql files should be phased out later on with the data store version control story. Going to close this as this is the best I think it can be for now.