Don't set event loop policy on Windows at import

Imports shouldn't have side effects like this.

Plus, with tornado 6.1 and pyzmq 22, proactor generally works anyway

Author: minrk

jupyter_client/utils.py

@@ -1,15 +1,11 @@
 """
 utils:
-- provides utility wrapeprs to run asynchronous functions in a blocking environment.
+- provides utility wrappers to run asynchronous functions in a blocking environment.
 - vendor functions from ipython_genutils that should be retired at some point.
 """
 import asyncio
 import inspect
 import os
-import sys
-
-if os.name == "nt" and sys.version_info >= (3, 7):
-    asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())  # type: ignore
 
 
 def run_sync(coro):