Apply suggestions from code review

Co-Authored-By: Michał Janiszewski <janisozaur@users.noreply.github.com>
Co-Authored-By: Aaron van Geffen <aaron@aaronweb.net>
Co-Authored-By: Tulio Leao <tupaschoal@gmail.com>

src/openrct2-ui/scripting/ScUi.hpp

@@ -46,7 +46,7 @@ namespace OpenRCT2::Scripting
         }
 
     private:
-        int32_t width_get()
+        int32_t width_get() const
         {
             return context_get_width();
         }