Update app-start.sh (#486)

add option to set HOST for uvicorn start command

We want to control the host for our deployment.

Author: Umaaz

Diff for: scripts/app-start.sh

@@ -1,6 +1,7 @@
 #!/usr/bin/env bash
 
 export PORT=${PORT:-8000}
+export HOST=${HOST:-"0.0.0.0"}
 export WORKERS=${WORKERS:-1}
 
 NUMREGEX="^[0-9]+$"
@@ -25,7 +26,7 @@ fi
 ${OPTIONAL_TIMEOUT} \
     uvicorn prepline_general.api.app:app \
     --log-config logger_config.yaml \
-    --host 0.0.0.0 \
+    --host "$HOST" \
     --port "$PORT" \
     --workers "$WORKERS" \