env is in /usr/bin, not in /bin

Change-Id: I9cfd84b2bd5a2381d517cde9d851f6c7250f8d91
Reviewed-on: https://gerrit.libreoffice.org/13563Reviewed-by: Arnaud Versini <arnaud.versini@libreoffice.org>
Tested-by: Arnaud Versini <arnaud.versini@libreoffice.org>

bin/lo-generate-source-tarball

-#!/bin/env bash
+#!/usr/bin/env bash
 
 if [ -n "$debug" ] ; then
 set -x