test: update karma npm from 3.1.4 to 6.4.2

[tnir]

Motivation / Background

karma npm package, used in actioncable and actionview, has been stale.

karma 3.x was stable in 2018, but 6.x is now the latest.

This Pull Request has been created because Rails developers are to use the latest karma and latest Node.js (20 LTS or 21).

Detail

This Pull Request updates karma package from 3.1.4 to 6.4.2, which prevents from using chokidar@2 (or fsevents@1).

Additional information

The package was introduced in #34440 and #46206. Also this change follows up #49901 (Node.js 20).

Checklist

Before submitting the PR make sure the following are checked:

• This Pull Request is related to one change. Changes that are unrelated should be opened in separate PRs.
• Commit message has a detailed description of what changed and why. If this PR fixes a related issue include it in the commit message. Ex: [Fix #issue-number]
• [n/a] Tests are added or updated if you fix a bug or add a feature.
• [n/a] CHANGELOG files are updated for the changed libraries if there is a behavior change or additional feature. Minor bug fixes and documentation changes should not be included.

[p8]

Thanks @tnir for the PR!
This looks good to me.
The UJS test run fine: https://buildkite.com/rails/rails/builds/101823#018bbee0-2b70-408f-a450-31a35384d114

[tnir]

@p8 Thanks. Any help on this PR?

[p8]

@zzak @yahonda Is this good to go?

[zzak]

FWIW, I had looked at this back in #48041 but haven't followed up. Been meaning to look at updating yarn.lock but, yeah not sure yet. Thank you for investigating!