fix: invoke Debian staging helper through bash

Author: mdheller

packaging/scripts/build-deb-package.sh

@@ -25,7 +25,7 @@ TURTLE_TERM_STAGE_PREFIX="$prefix" \
 TURTLE_TERM_ETC_DIR="$etc_dir" \
 TURTLE_TERM_RUNTIME_PREFIX="/usr" \
 TURTLE_TERM_RUNTIME_ETC_DIR="/etc" \
-  "$repo_root/packaging/scripts/stage-linux-package.sh" >/dev/null
+  bash "$repo_root/packaging/scripts/stage-linux-package.sh" >/dev/null
 
 cat > "$debian_dir/control" <<EOF
 Package: turtle-term