Maybe a faster, more dependeable dockerfile?

Dockerfile

@@ -1,15 +1,24 @@
-FROM sartography/cr-connect-python-base
+FROM python:3.8
+
+RUN pip install pipenv
+RUN useradd _gunicorn --no-create-home --user-group
+
+RUN apt-get update && \
+    apt-get install -y -q \
+        gcc libssl-dev \
+        curl postgresql-client git-core \
+        gunicorn3 postgresql-client
 
 WORKDIR /app
 COPY Pipfile Pipfile.lock /app/
+RUN cd /app && pipenv lock --keep-outdated --requirements > requirements.txt
+RUN pip install -r /app/requirements.txt
 
 RUN set -xe \
-  && pipenv install --dev \
   && apt-get remove -y gcc python3-dev libssl-dev \
   && apt-get autoremove -y \
   && apt-get clean -y \
-  && rm -rf /var/lib/apt/lists/* \
-  && useradd _gunicorn --no-create-home --user-group
+  && rm -rf /var/lib/apt/lists/*
 
 COPY . /app/
 WORKDIR /app