tests/payments/p2pk: fix wrong fixture names
tests/payments/p2pk: fix wrong fixture names

UdjinM6/bitcoinjs-lib-dash,BitGo/bitcoinjs-lib,BitGo/bitcoinjs-lib,bitcoinjs/bitcoinjs-lib,visvirial/bitcoinjs-lib,junderw/bitcoinjs-lib,visvirial/bitcoinjs-lib,junderw/bitcoinjs-lib,bitcoinjs/bitcoinjs-lib