tests: Adjust usage of NativeFunction according to previos changes

tests/functions.cpp

@@ -97,14 +97,14 @@ TEST_CASE("NativeFunction") {
 	SECTION("with return value") {
 		REQUIRE(luaL_dostring(state, "return function (x, y) return x + y end") == LUA_OK);
 
-		auto fun = luwra::read<luwra::NativeFunction<int(int, int)>>(state, -1);
+		auto fun = luwra::read<luwra::NativeFunction<int>>(state, -1);
 		REQUIRE(fun(13, 37) == 50);
 	}
 
 	SECTION("without return value") {
 		REQUIRE(luaL_dostring(state, "return function (x, y) returnValue = x + y end") == LUA_OK);
 
-		auto fun = luwra::read<luwra::NativeFunction<void(int, int)>>(state, -1);
+		auto fun = luwra::read<luwra::NativeFunction<void>>(state, -1);
 		fun(13, 37);
 
 		int returnValue = state["returnValue"];