xm126 test: "distance_mm" key is actually "distance mm"

Author: Johan Björnstedt

custom_components/ble_monitor/test/test_acconeer_parser.py

@@ -63,5 +63,5 @@ def test_acconeer_xm126_distance(self):
         assert sensor_msg["data"]
         assert sensor_msg["battery"] == 100
         assert sensor_msg["temperature"] == 22
-        assert sensor_msg["distance_mm"] == 1368
+        assert sensor_msg["distance mm"] == 1368
         assert sensor_msg["rssi"] == -62