list-objects-filter-options: error is localizeable

The "invalid filter-spec" message is user-facing and not a BUG, so make
it localizeable.

For reference, the message appears in this context:

	$ git rev-list --filter=blob:nonse --objects HEAD
	fatal: invalid filter-spec 'blob:nonse'

Signed-off-by: Matthew DeVore <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: matvore

list-objects-filter-options.c

@@ -84,7 +84,7 @@ static int gently_parse_list_objects_filter(
 	}
 
 	if (errbuf)
-		strbuf_addf(errbuf, "invalid filter-spec '%s'", arg);
+		strbuf_addf(errbuf, _("invalid filter-spec '%s'"), arg);
 
 	memset(filter_options, 0, sizeof(*filter_options));
 	return 1;