Error when passing the literal string " " to a function with bytes calldata as parameter

I am trying to implement the chainlink keeper to my contract. Actually I want to use the function checkUpkeep that is defined in this way:

function checkUpKeep(bytes calldata /* */) public returns (bool /* */, bytes memory /* */)

When I try to call this function with the literal string " " as parameter, solidity compiler (0.8.8) throw me this error:

TypeError: Invalid type for argument in function call. Invalid implicit conversion from literal_string "" to bytes calldata requested.

I call this function in this way:

checkUpKeep("")

My code:

function checkUpkeep(bytes calldata /* checkData */) public override returns (bool upkeepNeeded, bytes memory/* performData*/ ) {         bool isOpen = (RaffleState.OPEN == s_raffleState);         bool timePassed = ((block.timestamp - s_lastTimeStamp) > i_interval);         bool hasPlayers = (s_players.length > 0);         bool hasBalance = address(this).balance > 0;         upkeepNeeded = (isOpen && timePassed && hasPlayers && hasBalance);     }      function performUpkeep(bytes calldata /* performData */) external override{         (bool upkeepNeeded, ) = checkUpkeep(""); // Error here         ...     }