scripting: as of release 5, 'enum' is a keyword

Change-Id: Ia45890892f3a0fa89b4c1f97a4c169de5e25c593
Reviewed-on: https://gerrit.libreoffice.org/11860
Reviewed-by: Samuel Mehrbrodt <s.mehrbrodt@gmail.com>
Tested-by: Samuel Mehrbrodt <s.mehrbrodt@gmail.com>