fix eval

pkgs/applications/misc/yakuake/default.nix

···
     homepage = https://yakuake.kde.org;
     description = "Quad-style terminal emulator for KDE";
     maintainers = with lib.maintainers; [ fridh ];
-    licenses = lib.licenses.gpl2;
+    license = lib.licenses.gpl2;
   };
 }