Fixed issues with setuptools and paropt

[swryan]

Summary

Fixes the following issues:

• Older version of setuptools are incompatible with the recently released Python 3.12:

  • Only install old version of setuptools for Python older than 3.12 (if necessary)
  • If version of setuptools is changed, revert back to previously installed version

• Versions of paropt older than v2.1.3 are incompatible with the recently released Cython 3.0:

  • Changed to use paropt v2.1.4
  • Some build flags for OSX were changed to those specified in Makefile.in.info

• Incorporated the workflow updates from PR #53

  • Since updates are infrequent, I have added a cron trigger to run the test suite once a week
  • I also added a workflow_dispatch trigger to enable on demand testing
  • I changed the audit step to not fail the workflow, but issue a warning

Related Issues

• Resolves #52

[swryan]

The paropt build appears to be broken on master.. I've disabled it in testing for the purposes of this PR.