squash! Merge branch 'master' into validate-actions

GitHub keeps insisting on inventing conflicts with `master` that
local git knows don't exist, so I keep having to make merge
commits that remove its idiocy and then mark them for autosquash
manually. Someone please fix GitHub.

.github/workflows/check-sdist.yml

@@ -47,7 +47,7 @@ jobs:
         # release of a corresponding Cabal and friends. it can also be short since it's
         # highly unlikely that we are releasing really old branches.
         ghc:
-          ["9.10.1", "9.8.1", "9.6.1"]
+          ["9.12.1", "9.10.1", "9.8.1", "9.6.1"]
 
     steps: