Problem: regression tests do not pass on Ubuntu or Mac OS CI

[michael-okeefe]

Although regression tests pass locally and on CI for Windows and locally for Mac OS, they do not run successfully for Ubutu (GCC) or Mac OS on CI. It is not yet clear why there are subtle differences in the erin run command and its output. This task would investigate the root cause of the issue and get regression tests working on all platforms/compilers. In addition, the CI would be updated to run the additional checks automatically.

• enable successfully running regress.py on macos-latest on CI
• enable successfully running regress.py on ubuntu-latest on CI