bug: Link to an non existent Github account.

[SantiagoPittella]

The levels authored by @theethernaut (I think that this is his/her new nickname) have a broken link to the Github account.

Probably needs a change in the L11 in the authors.json

[GianfrancoBazzani]

Thank @SantiagoPittella for reporting this, changes have been introduced here: https://github.com/OpenZeppelin/ethernaut/pull/700/commits/6ec3c51da648436e006bc9f3f9f72582e67b8a57