Scripts: Refactor dist/heif-convert.sh

Signed-off-by: Michael Mayer <michael@photoprism.app>

Author: lastzero

scripts/dist/heif-convert.sh

@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
 
 if [[ -z $1 ]] && [[ -z $2 ]]; then
-    echo "Usage: heif-convert <filename> <output>" 1>&2
+    echo "Usage: ${0##*/} <filename> <output>" 1>&2
     exit 1
 fi