chore(package): update cross-env to version 7.0.0 (#663)
chore(package): update cross-env to version 7.0.0 (#663)

drops Node 8 support
opensheetmusicdisplay/opensheetmusicdisplay,opensheetmusicdisplay/opensheetmusicdisplay,opensheetmusicdisplay/opensheetmusicdisplay