Deprecated Counters.sol and use Math.sol

[takeumanorekishi]

in Section1 - Lesson 5
Counters.sol was deprecated on openzeppelin v5.0.1.
So, need to use Math.sol instead of Counters.sol.
https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v5.0.1/contracts/utils/math/Math.sol

• old MyEpicGame.sol

  import "@openzeppelin/contracts/utils/Counters.sol";
  ------
  using Counters for Counters.Counter;
  Counters.Counter private _tokenIds;
  ------
  _tokenIds.increment();
  

• new MyEpicGame.sol

  import "@openzeppelin/contracts/utils/math/Math.sol";
  -----
  using Math for uint256;
  uint256 private _tokenIds;
  -----
  (bool retFlg, uint256 retTokenIds) = _tokenIds.tryAdd(1);
  if (!retFlg) {
    revert ErrorHandling;
  }
  _tokenIds = retTokenIds;