Reformat Dockerfile to new renku standard

Dockerfile

 # For finding latest versions of the base image see
 # https://github.com/SwissDataScienceCenter/renkulab-docker
 ARG RENKU_BASE_IMAGE=renku/renkulab-py:3.10-0.25.0
+
+########################################################
+#                Renku install section                 #
+ARG RENKU_VERSION=2.9.4
+
+# Install renku from pypi or from github if a dev version
+RUN if [ -n "$RENKU_VERSION" ] ; then \
+        source .renku/venv/bin/activate ; \
+        currentversion=$(renku --version) ; \
+        if [ "$RENKU_VERSION" != "$currentversion" ] ; then \
+            pip uninstall renku -y ; \
+            gitversion=$(echo "$RENKU_VERSION" | sed -n "s/^[[:digit:]]\+\.[[:digit:]]\+\.[[:digit:]]\+\(rc[[:digit:]]\+\)*\(\.dev[[:digit:]]\+\)*\(+g\([a-f0-9]\+\)\)*\(+dirty\)*$/\4/p") ; \
+            if [ -n "$gitversion" ] ; then \
+                pip install --no-cache-dir --force "git+https://github.com/SwissDataScienceCenter/renku-python.git@$gitversion" ;\
+            else \
+                pip install --no-cache-dir --force renku==${RENKU_VERSION} ;\
+            fi \
+        fi \
+    fi
+#             End Renku install section                #
+########################################################
+
 FROM ${RENKU_BASE_IMAGE}
 
 # Uncomment and adapt if code is to be included in the image
@@ -23,29 +45,6 @@ RUN conda env update -q -f /tmp/environment.yml && \
     /opt/conda/bin/pip install -r /tmp/requirements.txt && \
     conda clean -y --all && conda list && \
     conda env export -n "root"
-RUN conda install -q -y -c conda-forge ffmpeg
+RUN conda install -q -y -c conda-forge ffmpeg  # could be removed, as not used?
 
-# RENKU_VERSION determines the version of the renku CLI
-# that will be used in this image. To find the latest version,
-# visit https://pypi.org/project/renku/#history.
-ARG RENKU_VERSION=2.9.4
-
-########################################################
-# Do not edit this section and do not add anything below
-
-# Install renku from pypi or from github if it's a dev version
-RUN if [ -n "$RENKU_VERSION" ] ; then \
-        source .renku/venv/bin/activate ; \
-        currentversion=$(renku --version) ; \
-        if [ "$RENKU_VERSION" != "$currentversion" ] ; then \
-            pip uninstall -y renku ; \
-            gitversion=$(echo "$RENKU_VERSION" | sed -n "s/^[[:digit:]]\+\.[[:digit:]]\+\.[[:digit:]]\+\(\.dev[[:digit:]]\+\)*\(+g\([a-f0-9]\+\)\)*\(+dirty\)*$/\3/p") ; \
-            if [ -n "$gitversion" ] ; then \
-                pip install --force "git+https://github.com/SwissDataScienceCenter/renku-python.git@$gitversion" ;\
-            else \
-                pip install --force renku==${RENKU_VERSION} ;\
-            fi \
-        fi \
-    fi
-
-########################################################
+COPY --from=builder ${HOME}/.renku/venv ${HOME}/.renku/venv