Address SDATE_GFS

[aerorahul]

Description
Fixes #1748

Type of change

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

How Has This Been Tested?
The regular CI tests will not catch this as METP requires to be run for a few cycles.

Checklist

• 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
• My changes need updates to the documentation. I have made corresponding changes to the documentation
• My changes generate no new warnings
• New and existing tests pass with my changes
• Any dependent changes have been merged and published

[RussTreadon-NOAA]

Tested proposed change in Hera EXPDIR. Change works as it should. The correct format SDATE_GFS was written to the EXPDIR xml file.

Approve.

[RussTreadon-NOAA]

Thank you @aerorahul for the quick response. The change works!