Improve many __(a)exit__ annotations (#9696)

stubs/mysqlclient/MySQLdb/cursors.pyi

@@ -29,7 +29,7 @@ class BaseCursor:
     def __init__(self, connection) -> None: ...
     def close(self) -> None: ...
     def __enter__(self): ...
-    def __exit__(self, *exc_info) -> None: ...
+    def __exit__(self, *exc_info: object) -> None: ...
     def nextset(self): ...
     def setinputsizes(self, *args) -> None: ...
     def setoutputsizes(self, *args) -> None: ...