ci: Add mypy as a dev dependency and configure it

examples/test_client.py

@@ -13,7 +13,7 @@ with open(os.path.expanduser("~/.ssb/secret"), encoding="utf-8") as f:
     config = yaml.safe_load(f)
 
 
-async def main():
+async def main() -> None:
     """Main function to run"""
 
     server_pub_key = b64decode(config["public"][:-8])

examples/test_server.py

@@ -8,17 +8,18 @@ from nacl.signing import SigningKey
 import yaml
 
 from secret_handshake import SHSServer
+from secret_handshake.network import SHSDuplexStream
 
 with open(os.path.expanduser("~/.ssb/secret"), encoding="utf-8") as f:
     config = yaml.safe_load(f)
 
 
-async def _on_connect(conn):
+async def _on_connect(conn: SHSDuplexStream) -> None:
     async for msg in conn:
         print(msg)
 
 
-async def main():
+async def main() -> None:
     """Main function to run"""
 
     server_keypair = SigningKey(b64decode(config["private"][:-8])[:32])