spectre-meltdown-checker: 0.39 -> 0.40
Semi-automatic update generated by
https://github.com/ryantm/nixpkgs-update tools. This update was made
based on information from
https://repology.org/metapackage/spectre-meltdown-checker/versions
(cherry picked from commit 4ca9524e987d2396c9a7aa4b44c205c7346bd2a6)
