Refactor: P2PKSecret (#323)

* port changes from dleq branch

* adjust tests

* fix tag serialization

* refactor p2pk and secrets into a new Protocol class

* clean up code

* refactor p2pk types from base

* test second refund pubkey

cashu/mint/main.py

@@ -47,7 +47,7 @@ def main(
         host=host,
         ssl_keyfile=ssl_keyfile,
         ssl_certfile=ssl_certfile,
-        **d,
+        **d,  # type: ignore
     )
     server = uvicorn.Server(config)
     server.run()