bpo-32296: Unbreak tests on Windows (#4850)

Lib/test/test_asyncio/test_events.py

@@ -2735,13 +2735,16 @@ class GetEventLoopTestsMixin:
         self.loop = asyncio.new_event_loop()
         asyncio.set_event_loop(self.loop)
 
+        if sys.platform != 'win32':
             watcher = asyncio.SafeChildWatcher()
             watcher.attach_loop(self.loop)
             asyncio.set_child_watcher(watcher)
 
     def tearDown(self):
         try:
+            if sys.platform != 'win32':
                 asyncio.set_child_watcher(None)
+
             super().tearDown()
         finally:
             self.loop.close()