Fix DaytimeMap error with disabled night missions.

Fixes https://github.com/dcs-liberation/dcs_liberation/issues/2429

game/timeofday.py

@@ -0,0 +1,10 @@
+from __future__ import annotations
+
+from enum import Enum
+
+
+class TimeOfDay(Enum):
+    Dawn = "dawn"
+    Day = "day"
+    Dusk = "dusk"
+    Night = "night"