Minor updates and housekeeping

[aerorahul]

This PR is a minor cleanup and housekeeping. Specifically,

• updates gitignore to include netcdf and grib2 files so they do not get committed to the repo
• updates the graphcast submodule pointer to the NOAA-EMC/graphcast instead of google-deepmind. This does not change the virtual envs.
• updates the environment.yml and pyproject.toml to be consistent.

[LinlinCui-NOAA]

Looks good to me. Thanks.

[RussellManser-NCO]

Looks good, I just have a question. Is it possible to make sure the graphcast commit hash is consistent between environment.yml and pyproject.toml? I see they are the same here, but I can imagine it's possible they get mismatched in the future.

[aerorahul]

Looks good, I just have a question. Is it possible to make sure the graphcast commit hash is consistent between environment.yml and pyproject.toml? I see they are the same here, but I can imagine it's possible they get mismatched in the future.

@RussellManser-NCO
Great question. This has been asked more times than I can remember. environment.yml is used by conda while pyproject.toml is used by pip, pipenv etc.
I have searched for an answer before and recently as well, and have not found a solution that works consistently and is simple enough. The accepted rule here is, deal with it, or drop one or the other, or don't enforce versions. I think dealing with it is more attractive than the alternatives.