Reformat Beok tests with black.

Fixes lint warnings.

tests/devices/test_beok_tr9b_thermostat.py

@@ -39,7 +39,7 @@ class TestBeokTR9BThermostat(
     MultiSelectTests,
     BasicSwitchTests,
     TargetTemperatureTests,
-    TuyaDeviceTestCase
+    TuyaDeviceTestCase,
 ):
     __test__ = True