[DOCS][BUILDBOT] Bump recommended worker version

[paschalis-mpeis]

Now recommend 3.11.7 to match the #testing-a-builder-config-locally section.

[DavidSpickett]

If you are using this worker version with llvm's master currently and it works, then this is fine.

Galina should be the approver though, because I know that the version used for the server right now is not the latest. Need to be sure it's compatible.

[paschalis-mpeis]

Hey @DavidSpickett,

Thanks for your review.

I know that the version used for the server right now is not the latest. Need to be sure it's compatible.

Yes, what you suggest sounds right to me.

To add a bit more context, I had a brief discussion with @gkistanova before opening the PR,
and there was no recollection of any issues with recent versions of buildbot-worker.

So I went ahead and updated the version to match the one suggested in the local configuration.
That said, I'm open to changing both places again, if we think a different recent version would be appropriate.

[DavidSpickett]

In that case this LGTM, will be good to have them in sync.

[paschalis-mpeis]

Thanks for the approval David. I'll wait @gkistanova to confirm as well.

[paschalis-mpeis]

Merging as there were no objections. This was confirmed outside of this review anyway. Thanks!