Update SC2 to v2.34.0

https://github.com/tmedwards/sugarcube-2/releases/tag/v2.34.0

Potentially interesting part for us:

• Fixed explicitly set undefined values within arrays being transformed into null when roundtripping through sessions/saves.

Basically variables set to undefined will now be deleted instead of being set to null after changing passage. Not too concerned about it, but there may be edge cases with unintended behavior.