Properly set gc mode for lua-5.4 [ci build]

extensions/scripting/lua-bindings/manual/CCLuaStack.cpp

@@ -94,6 +94,11 @@ namespace {
 
         return 0;
     }
+
+    int lua_version(lua_State* L) {
+        lua_pushinteger(L, LUA_VERSION_NUM);
+        return 1;
+    }
 }
 
 NS_CC_BEGIN
@@ -132,6 +137,7 @@ bool LuaStack::init()
     const luaL_Reg global_functions [] = {
         {"print", lua_print},
         {"release_print",lua_release_print},
+        {"version", lua_version},
         {nullptr, nullptr}
     };
     luaL_register(_state, "_G", global_functions);