fix yaml parser trim filename bug with gcc

[rem1776]

Description
fixes the parser output test failing from bad file names outputted with gcc + prod flags. Just needed to replace the function isspace with a char comparison and the trim works properly.

How Has This Been Tested?
make check on amd box with gcc 13 + prod flags

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
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules
• New check tests, if applicable, are included
• make distcheck passes