Challenge 4: fix error message for openzeppelin v5

[rin-st]

And remove openzeppelin v4 dependency

context: #245 (comment)

[rin-st]

Cause of the error:
I had this line in my solution code
require(token.transfer(msg.sender, tokenOutput), "ethToToken(): reverted swap.");

Since ERC20 transfer should return boolean and it worked before. But from current version ERC20.sol of openzeppelin

We have followed general OpenZeppelin Contracts guidelines: functions revert instead returning `false` on failure. This behavior is nonetheless  conventional and does not conflict with the expectations of ERC20 applications.

transfer follows that, and then in my code token.transfer(msg.sender, tokenOutput) is not boolean when there is an error inside transfer and hence error notification is broken

So if I just change that line everything works fine.

So I removed openzeppelin v4 requirement from the code 6cbf937

Closing the issue

cc @damianmarti

[damianmarti]

Cause of the error: I had this line in my solution code require(token.transfer(msg.sender, tokenOutput), "ethToToken(): reverted swap.");

Since ERC20 transfer should return boolean and it worked before. But from current version ERC20.sol of openzeppelin

We have followed general OpenZeppelin Contracts guidelines: functions revert instead returning `false` on failure. This behavior is nonetheless  conventional and does not conflict with the expectations of ERC20 applications.

transfer follows that, and then in my code token.transfer(msg.sender, tokenOutput) is not boolean when there is an error inside transfer and hence error notification is broken

So if I just change that line everything works fine.

So I removed openzeppelin v4 requirement from the code 6cbf937

Closing the issue

cc @damianmarti

Great! Thank you @rin-st !