Until the next release that removes template magic you should be doing this:
action:
- data_template:
message: >-
Dark Outside changed state to {{ states("binary_sensor.dark_outside") }} because of a combination of these values: {{ '\n' -}}
- Sun Elevation is {{ state_attr("sun.sun","elevation") }} {{ '\n' -}}
- OWM Cloud Coverage is {{ states("sensor.owm_cloud_coverage") }}
service: notify.mainplatform
- service_template: >-
{% if (is_state("binary_sensor.dark_outside","on")) -%}
script.driveway_lamp_high
{%- else -%}
script.driveway_lamp_off
{%- endif %}