fix(container-image): use wait-for-it package

Dockerfile

@@ -1,9 +1,7 @@
 FROM python:3.9.7-slim-buster@sha256:76eaa9e5bd357d6983a88ddc9c4545ef4ad64c50f84f081ba952c7ed08e3bdd6
 WORKDIR /app
 
-RUN apt-get update && apt-get install -y --no-install-recommends libpq-dev wget build-essential \
-&& wget -q https://raw.githubusercontent.com/vishnubob/wait-for-it/master/wait-for-it.sh -P /usr/local/bin \
-&& chmod +x /usr/local/bin/wait-for-it.sh \
+RUN apt-get update && apt-get install -y --no-install-recommends libpq-dev wget build-essential wait-for-it \
 && mkdir -p /app \
 && useradd -u 901 -r emeis --create-home \
 # all project specific folders need to be accessible by newly created user but also for unknown users (when UID is set manually). Such users are in group root.
@@ -27,4 +25,4 @@ COPY . $APP_HOME
 
 EXPOSE 8000
 
-CMD /bin/sh -c "wait-for-it.sh $DATABASE_HOST:${DATABASE_PORT:-5432} -- ./manage.py migrate && gunicorn --workers 10 --access-logfile - --limit-request-line 16384 --bind :8000 emeis.wsgi"
+CMD /bin/sh -c "wait-for-it $DATABASE_HOST:${DATABASE_PORT:-5432} -- ./manage.py migrate && gunicorn --workers 10 --access-logfile - --limit-request-line 16384 --bind :8000 emeis.wsgi"