Update PR template for code owners

[WalterKolczynski-NOAA]

Description

Adds a new checklist item for PRs that confirms any new scripts have been added to the CODEOWNERS file, along with owners.

Follow-up to #2996

Type of change

• Maintenance (code refactor, clean-up, new CI test, etc.)

Change characteristics

• Is this a breaking change (a change in existing functionality)? NO
• Does this change require a documentation update? NO
• Does this change require an update to any of the following submodules? NO

How has this been tested?

N/A

Checklist

• Any dependent changes have been merged and published
• 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 documented my code, including function, input, and output descriptions
• My changes generate no new warnings
• New and existing tests pass with my changes
• This change is covered by an existing CI test or a new one has been added
• I have made corresponding changes to the system documentation if necessary