GH Actions with linux (ubuntu)

[apcraig]

GH Actions is implemented in Icepack and CICE using a macos environment with conda. We'd like to also test the conda linux env, but some problems were encountered when linux (ubuntu) was tested. See CICE-Consortium/Icepack#347 for more information, but basically, csh is getting confused and we need to explore using bash. In earlier work, the bash base shell did not work in some of the scripts, but more investigation is needed.