Bug#1004066: groestlcoin: FTBFS pubkey.cpp:181:96: error: invalid conversion from 'secp256k1_xonly_pubkey*' to 'size_t'

[Bastian Germann]

This should be fixed with v25 which contains the following commit:
https://github.com/Groestlcoin/groestlcoin/commit/4462cb04986d77eddcfc6e8f75e04dc278a8147a