Breaking change in the new version of osrm

[rCarto]

Hello @Robinlovelace ,

I'll drop sp support in the next version of osrm. One effect of this is I have deprecated the use of returnclass arg in all relevant functions (including osrmRoute()). Functions will now exclusively return an sf object.
This change leads to a few warnings when checking stplanr (master and no-sp-2022 branches).

remotes::install_github("riatelab/osrm", ref = "refactor")

I could use a message instead of a warning (though it may not be the best practice). What do you think?

[Robinlovelace]

Great stuff, I'm also dropping sp soon as per #332 and #481. So good timing!

[Robinlovelace]

Happy for it to be a warning, will aim to fix my side.