bump-pom-scijava: refactor how maven-helper.sh is called
bump-pom-scijava: refactor how maven-helper.sh is called

We'll need this to detect the latest of the dependency versions listed
in pom-scijava.

Signed-off-by: Johannes Schindelin <53fb8db7833fca1e1746dd8592f61048d350f64c@gmx.de>

scijava/scijava-common