Fix shebang for helper script of deb-utils
Shebang was missing the ! between # and the actual path.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Martin Rüegg <martin.rueegg@metaworx.ch>
Closes #14339