Fix ocaml-version constraint on ppx_tools again

Ok, I'm not sure how exactly, but #2921 got the versions wrong. 0.99.1 and 0.99.2 work both on 4.02.0 and 4.02.1, but not on 4.03; 0.99 and 0.1 works only on 4.02.0. I've manually verified all the combinations to work.