Fix bouncer signature tests (#1915)
Fix bouncer signature tests (#1915)

* Fix bouncer signature tests

* Update GSNBouncerSignature.test.js

(cherry picked from commit 19a41980a17b0f5c7a125e8887c13cab26dfe1f2)

OpenZeppelin/zeppelin-solidity,OpenZeppelin/openzeppelin-contracts,OpenZeppelin/openzeppelin-contracts,OpenZeppelin/zep-solidity,OpenZeppelin/zep-solidity,OpenZeppelin/zeppelin-solidity,OpenZeppelin/openzeppelin-contracts