fix: use-after-free in `cbus_endpoint_delete`

Calling a `TRASH` macro after calling the `free`
function dereferences the pointer to the already
freed memory.

NO_DOC=picodata internal patch
NO_CHANGELOG=picodata internal patch
NO_TEST=picodata internal patch

src/lib/core/cbus.c

@@ -443,8 +443,8 @@ int
 cbus_endpoint_delete(struct cbus_endpoint *endpoint)
 {
 	cbus_endpoint_destroy_inner(endpoint, cbus_process);
-	free(endpoint);
 	TRASH(endpoint);
+	free(endpoint);
 	return 0;
 }