Ignore warnings about running pip as root in the Docker image.

Author: brycelelbach

build/dockerfile

@@ -4,6 +4,8 @@ COPY . /pyhpc-tutorial
 
 WORKDIR /pyhpc-tutorial/notebooks
 
+ENV PIP_ROOT_USER_ACTION=ignore
+
 RUN pip install --root-user-action ignore -r /pyhpc-tutorial/build/requirements.txt \
  && git config --unset-all "http.https://github.com/.extraheader" || { code=$?; [ "$code" = 5 ] || exit "$code"; } \
  && git config --global --add safe.directory "/pyhpc-tutorial" \