Missing project property on CI

[Matthew Cain]

Github CI build failed due to missing project property.

FAILURE: Build failed with an exception.

• Where:
  Script '/home/runner/work/pz-zdoc/pz-zdoc/setup.gradle' line: 38

• What went wrong:
  A problem occurred evaluating script.
  > Unable to find local project property game.dir

[Matthew Cain]

This issue is still not properly resolved, see failed build #77.