Update container base image from ubuntu:18.04 to ubuntu:20.04

CHANGELOG.txt

@@ -8,6 +8,7 @@ Changes in Release 2.2.0
    own code. You might have to adapt CMake flags when building OpenStructure to 
    variables specified here: 
    https://cmake.org/cmake/help/latest/module/FindPython.html
+ * Update container base image from ubuntu:18.04 to ubuntu:20.04
  * Several minor bug fixes and improvements.
 
 Changes in Release 2.1.0

docker/Dockerfile

-FROM ubuntu:18.04
+FROM ubuntu:20.04
 
 # ARGUMENTS
 ###########
@@ -98,7 +98,7 @@ RUN cd ${SRC_FOLDER} && \
 #############
 WORKDIR /home
 ENV OST_ROOT="/usr/local"
-ENV PYTHONPATH="/usr/local/lib64/python3.6/site-packages"
+ENV PYTHONPATH="/usr/local/lib64/python3.8/site-packages"
 ENV LD_LIBRARY_PATH="$LD_LIBRARY_PATH:/usr/local/lib64:/usr/local/openmm/lib/"
 ENV QT_X11_NO_MITSHM=1
 ENV OPENSTRUCTURE_VERSION=$OPENSTRUCTURE_VERSION

singularity/Singularity

 BootStrap: docker
-From: registry.scicore.unibas.ch/schwede/openstructure:2.2.0
+From: registry.scicore.unibas.ch/schwede/openstructure:2.2.0-focal
 %post
 ##############################################################################
 # POST
@@ -54,7 +54,7 @@ cat > $JUPYTER_PATH/kernels/ost-kernel/kernel.json <<EOF
     "-m", "ipykernel",
         "-f", "{connection_file}",
     "--InteractiveShellApp.exec_PYTHONSTARTUP=False",
-    "--InteractiveShellApp.exec_files=['/usr/local/lib64/python3.6/site-packages/ost/ost_startup.py']"
+    "--InteractiveShellApp.exec_files=['/usr/local/lib64/python3.8/site-packages/ost/ost_startup.py']"
   ],
   "env": {
   }
@@ -176,7 +176,7 @@ goes to CWD. Thus this sould work as expected out of the box.
 # NOTEBOOK ENV
 ##############################################################################
 export DNG_ROOT=$OST_ROOT
-export DNG_INITDIR=${DNG_ROOT}/lib64/python3.6/site-packages/ost
+export DNG_INITDIR=${DNG_ROOT}/lib64/python3.8/site-packages/ost
 
 
 %apprun IPython