pipewire: Ensure that the correct struct is used for enumeration APIs

PipeWire now requires the correct struct type is used, otherwise
it will fail to compile.

Reference: https://gitlab.freedesktop.org/pipewire/pipewire/-/commit/188d920733f0791413d3386e5536ee7377f71b2f

Fixes: https://github.com/libsdl-org/SDL/issues/12224

src/audio/pipewire/SDL_pipewire.c

@@ -548,7 +548,7 @@ static void node_event_info(void *object, const struct pw_node_info *info)
 
         // Need to parse the parameters to get the sample rate
         for (i = 0; i < info->n_params; ++i) {
-            pw_node_enum_params(node->proxy, 0, info->params[i].id, 0, 0, NULL);
+            pw_node_enum_params((struct pw_node*)node->proxy, 0, info->params[i].id, 0, 0, NULL);
         }
 
         hotplug_core_sync(node);