add sys version check on iscoroutine

Author: KotlinIsland

stdlib/asyncio/coroutines.pyi

@@ -1,3 +1,4 @@
+import sys
 import types
 from collections.abc import Callable, Coroutine
 from typing import Any, TypeVar
@@ -7,4 +8,7 @@ _F = TypeVar("_F", bound=Callable[..., Any])
 
 def coroutine(func: _F) -> _F: ...
 def iscoroutinefunction(func: object) -> bool: ...
-def iscoroutine(obj: object) -> TypeGuard[types.GeneratorType[Any, Any, Any] | Coroutine[Any, Any, Any]]: ...
+if sys.version_info < (3, 8):
+    def iscoroutine(obj: object) -> TypeGuard[types.GeneratorType[Any, Any, Any] | Coroutine[Any, Any, Any]]: ...
+else:
+    def iscoroutine(obj: object) -> TypeGuard[Coroutine[Any, Any, Any]]: ...