Migrate off of Fedora 39

The pipeline references a Fedora 39 image that is EOL (see https://github.com/dotnet/dotnet-buildtools-prereqs-docker/pull/1255):

https://github.com/dotnet/sdk/blob/2d87cb8327aa0d998bc5a5e34cbcf6585c8dc5af/.vsts-ci.yml#L75

https://github.com/dotnet/sdk/blob/2d87cb8327aa0d998bc5a5e34cbcf6585c8dc5af/.vsts-pr.yml#L31

This should be migrated to a supported version.