[mod] Make package_linter happier than ever.

scripts/backup

@@ -1,7 +1,7 @@
 #!/bin/bash
 
-echo "backup script is not implemented"
-exit 0
+ynh_die "backup script is not implemented"
+
 
 #=================================================
 # GENERIC START

scripts/restore

@@ -1,7 +1,7 @@
 #!/bin/bash
 
-echo "restore script is not implemented"
-exit 0
+ynh_die "restore script is not implemented"
+
 #=================================================
 # IMPORT GENERIC HELPERS
 #=================================================