Fix: Fixes a warning in utils-worker package for missing vm module

[vidorteg]

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For non-trivial changes, please make sure you also:

• Added/Updated related documentation.
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Short description of the change(s)

Recent builds have a warning when running the tests about a missing dependency that was used to be fullfilled

WARNING in ../../node_modules/asn1.js/lib/asn1/api.js 21:12-42
Module not found: Error: Can't resolve 'vm' in '/home/vidorteg/vidorteg-webhint/node_modules/asn1.js/lib/asn1'

BREAKING CHANGE: webpack < 5 used to include polyfills for node.js core modules by default.
This is no longer the case. Verify if you need this module and configure a polyfill for it.

If you want to include a polyfill, you need to:
        - add a fallback 'resolve.fallback: { "vm": require.resolve("vm-browserify") }'
        - install 'vm-browserify'
If you don't want to include a polyfill, you can use an empty module like this:

So applying the suggested fix