fix: add listings approval variable to docker file (#342)

build/docker/Dockerfile.sites-generic

@@ -11,6 +11,7 @@ ARG IDLE_TIMEOUT=5
 ARG LANGUAGES=en
 ARG MAPBOX_TOKEN
 ARG GTM_KEY
+ARG FEATURE_LISTINGS_APPROVAL
 
 # The base image will contain all the source code needed for our site
 FROM node:18.14-alpine AS base
@@ -113,6 +114,7 @@ ARG IDLE_TIMEOUT
 ARG LANGUAGES
 ARG MAPBOX_TOKEN
 ARG GTM_KEY
+ARG FEATURE_LISTINGS_APPROVAL
 
 # We need to have this nested 2 layers deep due to hardcoded paths in package.json
 WORKDIR /app/sites/${SITE}
@@ -130,6 +132,7 @@ ENV IDLE_TIMEOUT=$IDLE_TIMEOUT
 ENV LANGUAGES=$LANGUAGES
 ENV MAPBOX_TOKEN=$MAPBOX_TOKEN
 ENV GTM_KEY=$GTM_KEY
+ENV FEATURE_LISTINGS_APPROVAL=$FEATURE_LISTINGS_APPROVAL
 
 # Build/compile
 RUN yarn build