Bump opower to 0.15.9 (#155473)

Author: tronikos

homeassistant/components/opower/manifest.json

@@ -8,5 +8,5 @@
   "iot_class": "cloud_polling",
   "loggers": ["opower"],
   "quality_scale": "bronze",
-  "requirements": ["opower==0.15.8"]
+  "requirements": ["opower==0.15.9"]
 }

requirements_all.txt

@@ -37,7 +37,7 @@ def mock_opower_api() -> Generator[AsyncMock]:
         "homeassistant.components.opower.coordinator.Opower", autospec=True
     ) as mock_api:
         api = mock_api.return_value
-        api.utility = PGE
+        api.utility = PGE()
 
         api.async_get_accounts.return_value = [
             Account(