Use pelican debian package.

Dockerfile

@@ -1,27 +1,17 @@
-FROM debian:buster-slim
+FROM debian:bullseye-slim
 
 # Install dependencies
 RUN export DEBIAN_FRONTEND=noninteractive && \
     apt-get update --yes --fix-missing && apt-get upgrade --yes && \
     apt-get install --yes --no-install-recommends \
         apt-utils \
-        build-essential \
-        bash \
-        coreutils \
-        python-pip \
-        python-virtualenv \
-        python-dev \
-        python-setuptools
+        pelican
 
 # Install pelican and dependencies
 COPY files/start.sh /start.sh
-COPY files/requirements.txt requirements.txt
-RUN pip install wheel
-RUN pip install -r requirements.txt
 
 # Cleanup
-RUN apt-get autoremove --yes $build_dependencies && apt-get autoremove --yes && \
-    apt-get clean --yes && rm -rf /var/lib/apt/* /var/cache/apt/* /root/.cache
+RUN apt-get clean --yes && rm -rf /var/lib/apt/* /var/cache/apt/* /root/.cache
 
 EXPOSE 8000
 WORKDIR /srv/pelican