message: feat(issuer): Allow the Issuer contract to mint more tokens
diff: @@ -17,6 +17,7 @@ contract Issuer is Initializable, OwnableUpgradeable, UUPSUpgradeable {
  event CertificationRequestRevoked(address indexed _owner, uint256 indexed _id);
  event CertificateRevoked(uint256 indexed _certificateId);
  + event CertificateVolumeMinted(address indexed _owner, uint256 indexed _certificateId, uint256 indexed _volume);
  // Certificate topic - check ERC-1888 topic description
  uint256 public certificateTopic;
  @@ -231,6 +232,16 @@ contract Issuer is Initializable, OwnableUpgradeable, UUPSUpgradeable {
  );
  }
  + /// @notice Mint more volume to existing certificates
  + /// @param _to To whom the volume should be minted.
  + /// @param _certificateId The ID of the certificate.
  + /// @param _volume Volume that should be minted.
  + function mint(address _to, uint256 _certificateId, uint256 _volume) external onlyOwner {
  + registry.mint(_certificateId, _to, _volume);
  +
  + emit CertificateVolumeMinted(_to, _certificateId, _volume);
  + }
  +
  /// @notice Validation for certification requests.
  /// @dev Used by other contracts to validate the token.
  /// @dev `_requestId` has to be an existing ID.
  