fix polling return type typevar (Azure#25570)

Author: kristapratico

sdk/textanalytics/azure-ai-textanalytics/azure/ai/textanalytics/_lro.py

@@ -24,11 +24,12 @@
 _SUCCEEDED = frozenset(["succeeded", "partiallycompleted", "partiallysucceeded"])
 
 
-PollingReturnType = TypeVar("PollingReturnType", covariant=True)
+PollingReturnType = TypeVar("PollingReturnType")
+PollingReturnType_co = TypeVar("PollingReturnType_co", covariant=True)
 
 
 @runtime_checkable
-class TextAnalysisLROPoller(Protocol[PollingReturnType]):
+class TextAnalysisLROPoller(Protocol[PollingReturnType_co]):
     """Implements a protocol which returned poller objects are consistent with.
     """