chore: replace deprecated String.prototype.substr()

[CommanderRoot]

This PR contains a:

• [x] bugfix
• [ ] new feature
• [x] code refactor
• [ ] test update
• [ ] typo fix
• [ ] metadata update

Motivation / Use-Case

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

Breaking Changes

None

Additional Info

[codecov[bot]]

Codecov Report

Patch coverage: 83.33% and project coverage change: +0.27 :tada:

Comparison is base (c960801) 95.06% compared to head (7bd9c33) 95.33%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #336      +/-   ##
==========================================
+ Coverage   95.06%   95.33%   +0.27%     
==========================================
  Files          39       40       +1     
  Lines        1620     1908     +288     
==========================================
+ Hits         1540     1819     +279     
- Misses         80       89       +9     

Impacted Files	Coverage Δ
lib/Resolver.js	89.04% <50.00%> (+1.04%)	:arrow_up:
lib/AliasPlugin.js	100.00% <100.00%> (ø)
lib/DescriptionFilePlugin.js	100.00% <100.00%> (ø)
lib/DescriptionFileUtils.js	96.92% <100.00%> (ø)
lib/ResolverFactory.js	98.56% <100.00%> (+1.42%)	:arrow_up:
lib/getPaths.js	100.00% <100.00%> (ø)

... and 4 files with indirect coverage changes

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Do you have feedback about the report comment? Let us know in this issue.

[TheLarkInn]

@CommanderRoot congrats on your first time contribution to enhanced-resolve! 🎉 Thank you for the PR.