CI tests to build notebooks can pass even if notebooks fail

[jeffjennings]

prs.yml passes even if processes in bash loop(s) within Makefile fail. These loops should be updated to throw an error when a notebook build or convert (or dependency install) fails.

Fixed with set -e line in bash loops - see ~https://unix.stackexchange.com/a/340652~ https://github.com/orgs/community/discussions/26710