script: Replace calls to depreated luaL_openlib

src/script/lua_api/l_settings.cpp

@@ -334,7 +334,7 @@ void LuaSettings::Register(lua_State* L)
 
 	lua_pop(L, 1);  // drop metatable
 
-	luaL_openlib(L, 0, methods, 0);  // fill methodtable
+	luaL_register(L, nullptr, methods);  // fill methodtable
 	lua_pop(L, 1);  // drop methodtable
 
 	// Can be created from Lua (Settings(filename))