Release 1.2.0

CHANGES:

* remove dependency on astring (#28, @hannesm)
* use OCaml-CI (#27, @Leonidas-from-XIV, @verbosemode)
* bump required dune version to 2.0
* raise lower bound to ocaml 4.08.0; remove rresult dependency (#25, by @hannesm)

Distribution 1.1.0

Distribution 1.0.0

Distribution 0.0.2

Initial release