Fix bug where BNF IDs where validated too easily

src/enums/MDNodaRepository.php

@@ -782,7 +782,7 @@ public static function validateBnfId(string $id):string|false {
         }
         else $id = self::validateNumericId($id, ["https://catalogue.bnf.fr/ark:/12148/cb"]);
 
-        if ($id === false) {
+        if ($id === false || strlen($id) < 6) {
             return false;
         }