PostgreSQL Anonymizer: The secret salt and shift of anon are readable by any role in pg_roles or pg_db_role_setting

PostgreSQL restricts acces to the salt and shift via the `SHOW` command for users not member of `pg_read_all_settings`. But they are visible in `pg_db_role_setting` or `pg_roles` if they were set on the database, user or both. PostgreSQL Anonymizer's documentation recommends to use ALTER DATABASE / ALTER ROLE for the salt. The problem is resolved in PostgreSQL Anonymizer 3.3.0 and later versions.