I think you have to make an update on pub.dev. The version 0.5.* is not available.
Because photo 0.4.8 depends on photo_manager ^0.4.8 and no versions of photo match >0.4.8 <0.5.0, photo ^0.4.8 requires photo_manager ^0.4.8.
So, because flutter_doctor depends on both photo_manager ^0.5.1 and photo ^0.4.8, version solving failed.
Because flutter_doctor depends on photo ^0.5.0 which doesn't match any versions, version solving failed.
I think you have to make an update on pub.dev. The version 0.5.* is not available.