Improve deprecation warning and set stacklevel

Author: Carreau

ipykernel/inprocess/socket.py

@@ -32,7 +32,8 @@ def send_multipart(self, msg_parts, flags=0, copy=True, track=False):
     @classmethod
     def register(cls, other_cls):
         if other_cls is not DummySocket:
-            warnings.warn("SocketABC is deprecated.", DeprecationWarning)
+            warnings.warn("SocketABC is deprecated since ipykernel version 4.5.0.",
+                    DeprecationWarning, stacklevel=2)
         abc.ABCMeta.register(cls, other_cls)
 
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