Update PR template for code owners (NOAA-EMC#3020)

# 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 NOAA-EMC#2996

# Type of change
- [x] Maintenance (code refactor, clean-up, new CI test, etc.)

# Change characteristics
<!-- Choose YES or NO from each of the following and delete the other
-->
- 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
- [x] Any dependent changes have been merged and published
- [x] My code follows the style guidelines of this project
- [x] I have performed a self-review of my own code
- [x] I have commented my code, particularly in hard-to-understand areas
- [x] I have documented my code, including function, input, and output
descriptions
- [x] My changes generate no new warnings
- [x] New and existing tests pass with my changes
- [ ] This change is covered by an existing CI test or a new one has
been added
- [x] I have made corresponding changes to the system documentation if
necessary

.github/pull_request_template.md

@@ -72,4 +72,5 @@ Example:
 - [ ] 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
+- [ ] Any new scripts have been added to the .github/CODEOWNERS file with owners
 - [ ] I have made corresponding changes to the system documentation if necessary