JuliaStats/MixedModels.jl: v4.25.1

MixedModels v4.25.1 NEWS file. Diff since v4.25.0 NB: Closed issues and pull requests are sorted temporally and so may include backports to other versions or work in the development branch for an upcoming breaking release. Please see the NEWS file for changes sorted by release. Closed issues: restoreoptsum fails after change in JSON file structure in 4.25.0 (#774) Merged pull requests: More sophisticated checks in restoreoptsum. (#775) (@dmbates)