test(infra): mirror the new car_charging_now_response default in MockConfigProvider (#5338 review)

The shared test config still listed the old yes/on/enable/true default.
Add 'charging' so it matches fetch.py's default.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: chalfontchubby

apps/predbat/tests/test_infra.py

@@ -479,7 +479,7 @@ def get_default_config(self):
             "car_charging_exclusive": False,
             "car_charging_from_battery": False,
             "car_charging_planned_response": ["yes", "on", "enable", "true"],
-            "car_charging_now_response": ["yes", "on", "enable", "true"],
+            "car_charging_now_response": ["yes", "on", "enable", "true", "charging"],
             "combine_rate_threshold": 1.0,
             "combine_export_slots": True,
             "combine_charge_slots": True,