Julia 1.10 is now LTS instead of 1.6, consequences for us

[fingolfin]

Julia 1.10 is now the Julia LTS release.

Should we draw consequences from this? Some we might want to consider:

1. we might raise the minimal required version for OSCAR from 1.6 to something higher, possibly even 1.10
   • pro: some features (e.g. package extensions) don't work in 1.6
   • con: excludes users (does the gain justify it?)
   • more pros/cons?
2. we may wish to stop CI testing with 1.6 (even if we don't explicitly drop 1.6 support), as work needed for supporting it will increase over time
   • e.g. we just needed CI: add workaround for new gcc with julia 1.6 on github runners #4189 and a similar change now is required fro all our other packages that run OscarCI on Julia 1.6 as part of their CI tests.
   • to stick with my example from above: package extensions require Julia 1.9 so we could decide to use that as minimal version

To be clear: I am not strongly advocating for this, but the question came up in Slack and I think it would be good to make our plans on this explicit.

(Personally I wonder if it might be a bit soon for requiring 1.10, given that it was released Dec 26, 2023 and so is not even a year old. OTOH if people use juliaup as they IMHO should there isn't much of a reason why they couldn't just update to 1.10... )

[fingolfin]

We discussed this during triage:

• no general objections
• some suggestions to make a last release supporting 1.6 printing a warning that no new updates would be made
• however this then got a lot of concern that people might be happily using an older Julia and OSCAR and don't want to be nagged (so at the very least such a warning should include simple instructions for how to disable it)
• overall no consensus on this idea, but anyway, we don't need this right now (it could always be implemented after the fact as Julia allows us to release updates to 1.1.x and 1.2.x etc. even when e.g. 1.3.0 is already out)