Wrong return type on SequelizeStore.sync()?

[Jupp56]

Hi,
a quick typescript heads-up:
I think the return type of the sync() method on the SequelizeStore class should be a promise.

The sequelize docs show that syncing a model returns a promise here.
In line 71 of connect-session-sequelize.js, this promise is returned to the caller.

I'll open and link a PR.