removing dependency on specific selenium version
removing dependency on specific selenium version

this makes setup.py agree with Pipfile and Pipfile.lock
SergeyPirogov/selene,SergeyPirogov/selene,yashaka/selene,SergeyPirogov/selene,yashaka/selene,SergeyPirogov/selene,yashaka/selene,SergeyPirogov/selene,yashaka/selene