Fixed clamping order count in trading inventory

Argument order and types were all wrong.

Found due to -D_GLIBCXX_ASSERTIONS, consider enabling it for
experimental builds maybe?

fixes #75742

src/inventory_ui.cpp

@@ -3943,8 +3943,8 @@ void inventory_multiselector::on_input( const inventory_input &input )
         if( entry.is_selectable() ) {
             size_t const count = entry.chosen_count;
             size_t const max = entry.get_available_count();
-            size_t const newcount = std::clamp<size_t>( 0,
-                                    count + ( input.action == "INCREASE_COUNT" ? +1 : -1 ),
+            size_t const newcount = std::clamp<ssize_t>( count + ( input.action == "INCREASE_COUNT" ? +1 : -1 ),
+                                    0,
                                     max );
             toggle_entry( entry, newcount );
         }