I don’t recall any mention of this in the release note. By bitmap do you mean that you hand draw the text? If you do there are other solution.
You could have photon display each character in a PhImage, then rotate that bitmap and then display it. At startup the program could create all symbol at first and then it would be failry easy to write a fonction that display a string verticaly using the PhImage (one per character).
Another solution is to create some custom font that are rotated. Still can’ use Photon text primitive to display a string but you could at least display each character one by one.