[v20x backport] deps: update undici to 6.19.8

[snyamathi]

Update Undici to v6.19.8 using ./tools/dep_updaters/update-undici.sh

This will backport nodejs/undici#3445 to v20 and close the loop on #54274 (comment)

If you believe this PR should be highlighted in the Node.js CHANGELOG
please add the notable-change label.

I don't think I'm able to add a label to this PR, but I believe this should be in the CHANGELOG

All tests passed.

Test pass locally when running make -j4 test

[nodejs-github-bot]

Review requested:

• @nodejs/security-wg

[mcollina]

I don't think there is a need for this, the commit should be backportable. However, we have a 2 week grace time after releasing something in the current release before backporting.

The undici update would go in the next release.

[snyamathi]

Thanks @mcollina I had missed the docs in https://github.com/nodejs/node/blob/main/doc/contributing/backporting-to-release-lines.md which explain that process