More adaptation for pydcs updates.

This is as much as we can do until pydcs actually adds the py.typed
file. Once that's added there are a few ugly monkey patching corners
that will just need `# type: ignore` for now, but we can't pre-add those
since we have mypy warning us about superfluous ignore comments.

gen/environmentgen.py

@@ -22,7 +22,7 @@ class EnvironmentGenerator:
     def set_fog(self, fog: Optional[Fog]) -> None:
         if fog is None:
             return
-        self.mission.weather.fog_visibility = fog.visibility.meters
+        self.mission.weather.fog_visibility = int(fog.visibility.meters)
         self.mission.weather.fog_thickness = fog.thickness
 
     def set_wind(self, wind: WindConditions) -> None: