Etherscan Contract validation

Hi, i try to verify my already deployed contract as in Remix i have no errors.

my contract code:

pragma solidity ^0.8.5;

// SPDX-License-Identifier: MIT

import 'https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/ERC20.sol';


contract Crillux is ERC20 {
    address public admin;
    constructor() ERC20 ('Crillux', 'Cril') {
        _mint(msg.sender, 300000000 * 10 ** 18);
        admin = msg.sender;
    }
    
        function burn(uint amount) external {
        _burn(msg.sender, amount);
    }
}

and thats the error i get:
ParserError: Source "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/ERC20.sol" not found: File import callback not supported
--> myc:5:1:
|
5 | import 'https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/ERC20.sol'
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
can someone please help?
thanks

Etherscan doesn't know how to do imports directly from openzeppelin's github. Flatten the file and try again.