Lottery game with solidity, only the manager can pick a winner

Lottery.sol

// SPDX-License-Identifier: GPL-3.0

pragma solidity >=0.7.0 <0.9.0;

 contract Lottery {
    address public manager_address;
    address[] public players;

    constructor() {
        manager_address = msg.sender;
    }

    function enter() public payable {
      // if the value is less the transaction will be reverted
        require(msg.value > 0.1 ether);

        players.push(msg.sender);
    }

    function pickWinner() public restricted payable {
      // generate a random index based on the pseudorandom value
        uint index = random() % players.length;
        payable(players[index]).transfer(address(this).balance);
        delete players;
    }

    function random() private view returns(uint) {
      // create a pseudorandom value
        return uint(keccak256(abi.encodePacked(block.difficulty, block.timestamp, players)));
    }

    function getPlayers() public view returns(address[] memory) {
        return players;
    }

    modifier restricted() {
        require(msg.sender == manager_address);
        _;
    }
 }