TST: Try putting fortran in own directory

[rstoneback]

Description

Addresses #(issue)

Started this looking for ways to get coverage working. First thought was that it may be related to a difference in file organization between OMMBV and apexpy. Further investigation revealed that it was primarily an issue with how the coveralls pytest command was constructed. Coveralls coverage reporting is now driven by the source files, not test files, and reporting to the coveralls website is working again!

So the Fortran files don't actually need to be in their own directory but here we are now.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Manual interactions with coveralls webpage as well as the unit tests run by GitHub actions.

Checklist:

• Make sure you are merging into the develop (not master) branch
• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• Add a note to CHANGELOG.md, summarizing the changes