Fix CI failure in russound_rio (#133081)

* Fix CI in russound_rio

* Adjust

homeassistant/components/russound_rio/media_player.py

@@ -3,6 +3,7 @@
 from __future__ import annotations
 
 import logging
+from typing import TYPE_CHECKING
 
 from aiorussound import Controller
 from aiorussound.const import FeatureFlag
@@ -157,6 +158,8 @@ def source(self) -> str:
     @property
     def source_list(self) -> list[str]:
         """Return a list of available input sources."""
+        if TYPE_CHECKING:
+            assert self._client.rio_version
         available_sources = (
             [
                 source