make some dilation objects hashable

necessary to include them in a set like _pending_connectors

src/wormhole/_dilation/connection.py

@@ -393,7 +393,7 @@ class _Record(object):
         self._framer.send_frame(frame)
 
 
-@attrs
+@attrs(hash=True)
 class DilatedConnectionProtocol(Protocol, object):
     """I manage an L2 connection.
 

src/wormhole/_dilation/connector.py

@@ -39,7 +39,7 @@ NOISEPROTO = b"Noise_NNpsk0_25519_ChaChaPoly_BLAKE2s"
 def build_noise():
     return NoiseConnection.from_name(NOISEPROTO)
 
-@attrs
+@attrs(hash=True)
 @implementer(IDilationConnector)
 class Connector(object):
     _dilation_key = attrib(validator=instance_of(type(b"")))

src/wormhole/_dilation/manager.py

@@ -87,7 +87,7 @@ def make_side():
 # * if follower calls w.dilate() but not leader, follower waits forever
 #   in "want", leader waits forever in "wanted"
 
-@attrs
+@attrs(hash=True)
 @implementer(IDilationManager)
 class Manager(object):
     _S = attrib(validator=provides(ISend))