bugfix for moonraker update manager

- add symbolic links to python3.9 to make moonraker happy

klipper/Dockerfile

@@ -78,6 +78,9 @@ RUN useradd --user-group --no-log-init --shell /bin/false -m -d ${HOME} ${USER}
     mkdir -p /var/log/klipper && chown ${USER}:${USER} /var/log/klipper && \
     pip install --no-cache supervisord-dependent-startup gpiod
 
+RUN mkdir -p /usr/lib/python3 && ln -s /usr/local/lib/python3.9/site-packages /usr/lib/python3/dist-packages
+RUN mkdir -p ${HOME}/moonraker-env/lib/ && ln -s ${HOME}/moonraker-env/lib/python3.9 ${HOME}/moonraker-env/lib/python3.7
+
 USER ${USER}
 WORKDIR ${HOME}