Remove unused dependencies

[rmccar]

What is the context of this PR?

This PR removes the minimist and js-beautify dependencies because they are no longer used.

Part of the fix for this ONSdigital/design-team#9

How to review this PR

• Tests pass
• Able to spin up the DS and see it working as expected

Checklist

This needs to be completed by the person raising the PR.

• I have selected the correct Project for this PR (Design System) and selected the correct status
• I have selected the correct Assignee
• I have linked the correct Issue

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