Update Dockerfile

Include sphinx-related binaries in the docker file for CI.

Dockerfile

@@ -5,7 +5,8 @@ LABEL NAME="sassena-ci" \
 RUN apt-get update -y
 RUN apt-get install -y build-essential cmake zlib1g-dev libblas-dev libfftw3-dev libxml2-dev libhdf5-dev wget mpi-default-dev liblapack-dev \
     ninja-build doxygen sphinx-doc
-
+RUN apt-get install -y python3 python3-pip
+RUN pip3 install doxysphinx sphinx-rtd-theme
 ARG BOOST_VERSION=1.80.0
 RUN cd /tmp && \
     BOOST_VERSION_MOD=$(echo $BOOST_VERSION | tr . _) && \