Probably we should consider Azure instead Travis. We need to evaluate Azure pipelines vs Github actions vs Travis vs DockerHub

It boils down to solving z3 build on MinGW OCaml port:

• Try to use GitHub Actions #1115 (comment)
• fdopen/opam-repository-mingw@7ca1bb1

We can use Github Actions too for windows support, moreover I believe it would be more practical. And yes, it all distills to z3 and llvm dependencies.

Note that Z3 package was fixed: https://github.com/fdopen/opam-repository-mingw/blob/opam2/packages/z3/z3.4.8.9/opam