home: atuin: use 'uk' dialect for dates

This should be for date *parsing*, from my looking at the code.

Unlikely to be relevant, but might as well set it to the saner of the
two options.

modules/home/atuin/default.nix

@@ -21,6 +21,8 @@ in
       ];
 
       settings = {
+        # Reasonable date format
+        dialect = "uk";
         # The package is managed by Nix
         update_check = false;
         # I don't care for the fancy display