girepository/girmodule: Cleanup the temporary dependencies string

It's used during build phase, as a temporary variable but never freed

girepository/girmodule.c

@@ -592,6 +592,7 @@ gi_ir_module_build_typelib (GIIrModule *module)
   g_hash_table_destroy (strings);
   g_hash_table_destroy (types);
   g_list_free (nodes_with_attributes);
+  g_free (dependencies);
 
   return typelib;
 }