Maintenance/Update MOM6

[sanAkel]

This PR adjusts CMakeLists.txt to be able to work with updates from mom-ocean/MOM6#1603

To do:

• ✅ @sanAkel: once GFDL candidate branch to main (2023-07-03) mom-ocean/MOM6#1603 has been merged submit this PR.
• @mathomp4 and/or @tclune: https://github.com/orgs/GEOS-ESM/teams/cmake-team review this PR.
• @mathomp4: please update our fork: https://github.com/GEOS-ESM/MOM6

[mathomp4]

@sanAkel I've updated the MOM6 fork and approved this.

Next up would be tags of both MOM6 and Ocean so we can get the tags up to GEOSgcm so the CI here can work again.

[sanAkel]

@sanAkel I've updated the MOM6 fork and approved this.

Next up would be tags of both MOM6

@mathomp4 ⬆️ is ✅ https://github.com/GEOS-ESM/MOM6/releases/tag/geos%2Fv2.2.1

and Ocean so we can get the tags up to GEOSgcm so the CI here can work again.

@mathomp4 this is also ✅ https://github.com/GEOS-ESM/GEOS_OceanGridComp/releases/tag/v2.1.2