chore: replace deprecated String.prototype.substr()

[CommanderRoot]

Why:

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.

What's being changed:

On one line substr(1) is being changed to slice(1). Both return the same values.

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  • I have added the 'writer impact' label
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[welcome]

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[github-actions]

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[ramyaparimi]

@CommanderRoot
Thanks so much for opening a PR! I'll get this triaged for review ⚡

[rsese]

thank you 👍 !

[github-actions]

👋 Hey there spelunker. It looks like you've modified some files that we can't accept as contributions. The complete list of files we can't accept are:
.devcontainer/**
.github/actions-scripts/**
.github/workflows/**
.github/CODEOWNERS
assets/fonts/**
data/graphql/**
Dockerfile*
lib/graphql/**
lib/redirects/**
lib/rest/**
lib/webhooks/**
lib/search/indexes/**
package*.json
scripts/**
translations/**
content/actions/deployment/security-hardening-your-deployments/**

You'll need to revert all of the files you changed in that list using GitHub Desktop or git checkout origin/main <file name>. Once you get those files reverted, we can continue with the review process.

[github-actions]

Thanks very much for contributing! Your pull request has been merged 🎉 You should see your changes appear on the site in approximately 24 hours. If you're looking for your next contribution, check out our help wanted issues ⚡