fix: run heredoc with `set -ex` for fast fail
Avoid builds that seem to succeed but that actually failed, e.g. https://eicweb.phy.anl.gov/containers/eic_container/-/jobs/2094238#L2278.
Edited by Wouter Deconinck
Avoid builds that seem to succeed but that actually failed, e.g. https://eicweb.phy.anl.gov/containers/eic_container/-/jobs/2094238#L2278.