refactor: replace deprecated String.prototype.substr()

[CommanderRoot]

Description

String.prototype.substr() is deprecated so we replace it with String.prototype.slice() which works similarily but isn't deprecated.
.substr() probably isn't going away anytime soon but the change is trivial so it doesn't hurt to do it.

Related Issue

Motivation and Context

String.prototype.substr() is deprecated

How Has This Been Tested?

I tested the return of each statement to make sure it's still the same as before

Screenshots (if appropriate):

Types of changes

• 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 change)
• Technical debt
• Tests only (no source changes)

Checklist:

• Code changes
• Unit tests added
• Acceptance tests added
• Documentation ticket raised:

[update-docs]

Thanks for opening this pull request! The maintainers of this repository would appreciate it if you would create a changelog item based on your changes.

[sonarqubecloud]

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0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

0.0% Coverage
0.0% Duplication