instrumentation/asyncio: catch CancelledError exception in tests

After a29242f we are re-raising the
CancelledError so we need to catch it on the caller side.

Fix open-telemetry#2688

instrumentation/opentelemetry-instrumentation-asyncio/tests/test_asyncio_cancellation.py

@@ -45,7 +45,10 @@ def tearDown(self):
 
     def test_cancel(self):
         with self._tracer.start_as_current_span("root", kind=SpanKind.SERVER):
-            asyncio.run(cancellation_create_task())
+            try:
+                asyncio.run(cancellation_create_task())
+            except asyncio.CancelledError:
+                pass
         spans = self.memory_exporter.get_finished_spans()
         self.assertEqual(len(spans), 3)
         self.assertEqual(spans[0].context.trace_id, spans[1].context.trace_id)