Only run a single CI job on Julia 1.9? #980
Description
The total (across all jobs) CI time on this repo is starting to get pretty long.
Julia 1.10 is the new LTS, so we should keep running all jobs on 1.10.
Julia 1.11 is currently the latest stable release, so we should continue running all jobs on 1.11, at least as long as it is the latest stable release.
Julia 1.9 is no longer supported, and there will not be any more patch releases of Julia 1.9. So I think we can probably just run a single Julia 1.9 CI job on this repo.
Julia 1.6 is no longer the LTS, but it was the LTS for a very long time, so at least in the short-term I think that we should keep running all jobs on 1.9.