curve public keys longer than beacon size

[smalls12]

As per https://rfc.zeromq.org/spec/43/, the beacon for an encrypted node includes 32 bytes for the server's public key.

Using the scripts from pyzmq to build the certificates, the public keys are 40 bytes long.
https://github.com/zeromq/pyzmq/blob/main/examples/security/generate_certificates.py

aspyre is therefore using 40 byte keys in the beacon.