v0.6.1

• Bump minimum ppxlib version to 0.18.0 to fix #49.

v0.6.0

• Migrate to ppxlib thanks to the contributions of @mseri to hopefully avoid most future breakage with new OCaml releases. This also necessitated dropping OCaml 4.04 support.
• Switch from Travis to GitHub Actions CI to keep up to date with OCaml images and leverage @avsm's setup-ocaml.

Merge pull request #46 from hammerlab/rev0.5.1

Update .opam and prep for release

v0.5.0: Merge pull request #44 from trepetti/ocaml-4.10.0

Enable OCaml 4.10.0. (Fixes #40.)