Change on from string to array, consistent with other definitions

[stefandoorn]

Q	A
Branch?	1.8
Bug fix?	no
New feature?	no
BC breaks?	no
Deprecations?	no
License	MIT

Nothing major, but the command bin/console debug:winzou:state-machine sylius_shipment errors due to a parsing bug in the underlying bundle. But next to that, this way is inconsistent with Sylius docs & the declaration below, so I think it's still good to adjust this in Sylius also.

[Zales0123]

The base of this pull-request was changed, you need fetch and reset your local branch
if you want to add new commits to this pull request. Reset before you pull, else commits
may become messed-up.

Unless you added new commits (to this branch) locally that you did not push yet,
execute git fetch origin && git reset "winzou" to update your local branch.

Feel free to ask for assistance when you get stuck 👍

[Zales0123]

Thanks, Stefan! 🥇