[Wallet/mint] P2PK with timelocks (#270)

* p2pk with nostr privatekey and timelocks

* add p2pk

* fix test

* fix test with custom secret

* sign whole split transaction

* p2pk signature now commits to entire secret and thus to a nonce

* use schnorr signatures

* revamp P2SH and P2PK with new Secret model

* test p2pk

* add comments

* add nostr private key to tests

* fix nostr receive

* make format

* test redemption after timelock

* refactor Server.serialize()

* sign sha256(secret)

* add optional refund pubkey that triggers after timelock

* use nostr private key for now (including nsec parser)

* use nostr private key and fix tests

* bump version to 0.12.2

tests/conftest.py

@@ -1,5 +1,6 @@
 import multiprocessing
 import os
+import secrets
 import shutil
 import time
 from pathlib import Path
@@ -58,6 +59,7 @@ def mint():
     settings.port = 3337
     settings.mint_url = "http://localhost:3337"
     settings.port = settings.mint_listen_port
+    settings.nostr_private_key = secrets.token_hex(32)  # wrong private key
     config = uvicorn.Config(
         "cashu.mint.app:app",
         port=settings.mint_listen_port,