build: include wait-for-it in final image

Dockerfile

@@ -27,7 +27,7 @@ ENV AURA_GID=${AURA_UID}
 
 RUN set -e \
   && apt-get update -q \
-  && apt-get install -y -q --no-install-recommends ffmpeg ca-certificates netcat-openbsd \
+  && apt-get install -y -q --no-install-recommends ffmpeg ca-certificates netcat-openbsd wait-for-it \
   && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
 
 RUN set -e \