Upgrade `ocamlfind` to 1.9.8 in lockfiles?

[michael-schwarz]

As of earlier today, our builds are failing as we use ocamlfind.1.9.6 and the camlcity.org website where the tarball for old versions is hosted seems to be offline.

Is anything blocking us from going to 1.9.8, where they now distribute via github?

[sim642]

I bumped it directly on master now.