Loosen h2o version requirement

[ledell]

We might consider changing the version requirement in requirements.txt to <3.36.0.2 (or put a lower bound on it), so that users can have more flexibility in using it with an existing/installed version of h2o on their machine.

If we want people to be able to use earlier versions of h2o (e.g. below 3.32.1.1), then we need to abstract some of the leaderboard code a bit more. The "algo" column was only added in 3.32.1.1, for example. And other extended leaderboard columns were added in prior versions (3.28.0.1).

If we add learning curve, that was also not added to some specific recent version of h2o, etc.