But I don't want to deploy only the ERC20PresetMinterPauser. I want to inherit from that contract and add some functions. But I'm not sure how to call the constructor in the child contract

Is this what you're looking for?
pragma solidity ^0.6.2;

import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v3.2.0/contracts/presets/ERC20PresetMinterPauser.sol";

contract Minter is ERC20PresetMinterPauser
{
constructor() public
ERC20PresetMinterPauser("name", "symbol") {
string memory test = "test";
}

}