update comment in conda lock creation Github action

[valeriupredoi]

Description

Thanks to @bettina-gier for noticing the comment is slightly out of date, this one here is a lot more useful for us to get to unpin mamba when conda-lock==3 is finally out. Cheers, Tina :beer:

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• [x] 🛠 ~All checks below this pull request were successful~ docs fail as per usual (new config configs)