NodeBB and RFC 9421

@skavish@welley.social said: same header name, two languages that don't mix. Yes, I was worried about this. I was hoping maybe cavage parsers were smart enough to only parse header values that match expected inputs, so sending two Signature headers would work, but knowing what I know, that's wishful thinking :sweat_smile: Thanks for the detailed reply! Looking forward to testing in the next few days.