OCaml version is currently 4.12.0. This version was released 2021-02-24.
If you could upgrade to OCaml 4.14.0 it would be nice since some features were added that are really useful (and if you can add str.cma to the linked libraries when compiling, that would be a nice bonus, this is not a third party package, it comes with the standard library but you need to opt in to use it)