Update dune version

[shonfeder]

Moving ocaml/infrastructure#82 (as per ocaml/infrastructure#82 (comment))

We need to update the dune lang version in Dune itself to 3.11 in order to start using some feature. However the bench job we have setup is running some commands using dune 3.10 which get stuck when our project version is 3.11. Any chance we can bump this dune version found in the image? Or better yet remove those commands entirely as they aren't really useful for Dune itself?

PR in question:

• chore: update dune-project version to 3.11 ocaml/dune#9212

The current version is 3.16.

It long term, we should probably look at automating this so we can stay up to date with the latest version.