Fix issue with when using --simenddate

Description

Fixes issue when running with --simenddate where variable format was incorrect

Fixes # (issue)

Please make your selection.

[x] Bug fix (non-breaking change which fixes an issue)
[ ] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
[ ] This change requires a documentation update
[ ] This change requires a new dependency
[ ] Code Maintainability / comments
[ ] Code Refactoring / future-proofing

Running locally

[x] My code follows the style guidelines of this project
[x] 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
[x] My changes generate no new warnings
[ ] I have added pytest unit 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
[x] I have checked my code and corrected any misspellings