Unsupported old <script setup> (last support in 0.18.17)

[johnsoncodehk]

The new <script setup> RFC is staging in vue@3.0.3 now: vuejs/rfcs#227 (comment)

I'm plan to remove the old <script setup> support after January 1, 2021.

I don't want to cause inconvenience to anyone, if you need to extend the time or have other ideas, please let me know!

[johnsoncodehk]

Last support in 0.18.17, if it affects you please don't update to 0.19.