home: jujutsu: set 'ui.pager'

The v0.36 release stopped honoring `$PAGER`. So enforce it in the
configuration (as I don't like their default pager settings).

Ideally this would be `mkIf`ed behind `my.home.pager.enable`, however it
looks like this does not work with the TOML type (does not seem to do
any `mkMerge`-ish logic).

modules/home/jujutsu/default.nix

@@ -43,6 +43,8 @@ in
         ui = {
           # I don't like word-diff
           diff-formatter = ":git";
+          # Does not honor `$PAGER` (anymore)
+          pager = lib.mkDefault config.home.sessionVariables.PAGER;
         };
 
         "--scope" = [