feat(paperless-ngx): Add missing var and a health check to upstream repo patch

paperless_ngx/build-context/Dockerfile

@@ -1,14 +1,6 @@
-# For the remainder of this Dockerfile EXAMPLE_ARG_FOR_DOCKERFILE will be
-# available with a value of 'must_be_available_in_dockerfile', check out the env
-# file at 'env/fully.qualified.domain.name.example' for reference.
-# ARG EXAMPLE_ARG_FOR_DOCKERFILE
+ARG PGSQL_VERSION
 
-# Another env var, this one's needed in the example build step below:
-# ARG PAPERLESS_NGX_VERSION
-
-# Example
-# FROM "paperless_ngx:${PAPERLESS_NGX_VERSION}"
-# RUN apt-get update && \
-#     apt-get -y install \
-#     somepackage-6.q16-6-extra && \
-#     rm -rf /var/lib/apt/lists/*
+FROM "docker.io/library/postgres:${PGSQL_VERSION}"
+RUN apt-get update && \
+    apt-get -y install iputils-ping && \
+    rm -rf /var/lib/apt/lists/*