Fix unitless converter missing valid units (#152665)

homeassistant/util/unit_conversion.py

@@ -742,6 +742,8 @@ class UnitlessRatioConverter(BaseUnitConverter):
     }
     VALID_UNITS = {
         None,
+        CONCENTRATION_PARTS_PER_BILLION,
+        CONCENTRATION_PARTS_PER_MILLION,
         PERCENTAGE,
     }
 

tests/components/sensor/test_recorder.py

@@ -5201,7 +5201,7 @@ async def test_validate_statistics_unit_ignore_device_class(
             BATTERY_SENSOR_ATTRIBUTES,
             "%",
             None,
-            "%, <None>",
+            "%, <None>, ppb, ppm",
         ),
     ],
 )