use latest image; add APP_ITERATIONS; fix boolean value

Author: coding-lemur

docker-compose.yml

@@ -1,7 +1,7 @@
-version: '3.7'
+version: '2'
 services:
     app:
-        image: mceddy/smartdisplay-server
+        image: mceddy/smartdisplay-server:latest
         environment:
             MQTT_SERVER: 'mqtt://localhost:1883'
             MQTT_USERNAME: 'user'
@@ -11,6 +11,7 @@ services:
             APP_CITY_WEATHER_APP_ID: 'your OpenWeather API key'
             APP_CITY_WEATHER_UNITS: 'metric'
             APP_CITY_WEATHER_MAX_CACHE_AGE: 30
-            APP_CITY_WEATHER_PUBLISH_DATA: false
+            APP_CITY_WEATHER_PUBLISH_DATA: 'false'
+            APP_ITERATIONS: 8
             TZ: 'Europe/Berlin'
         restart: unless-stopped