Make test gdnlib not-relodable

Fixes crashes due to hot-reloading changes in godot 3.3 that cause reloadable libraries to be terminated when no NativeScripts remain referencing them.

Author: Waridley

test/project/gdnative.gdnlib

@@ -16,4 +16,4 @@ X11.64=[  ]
 singleton=false
 load_once=true
 symbol_prefix="godot_"
-reloadable=true
+reloadable=false