add dhall types Name, Version, Revision, Subdir, Url

Add modPackageSet to change modifiers of an entire package set at once

See merge request horizon/horizon-spec!6

Add PackageSet type

See merge request horizon/horizon-spec!5

vm-test (check): init
dhall-horizon-spec (package): add

Add golden test suite

See merge request horizon/horizon-spec!4

Add PackageSet type with compiler and packages fields

HsPkg -> HaskellPackage

horizon-platform: a5cf531157093f7a991066a35149e06344d826fd -> c015424c88bd95cfb40c27639d073a3209ffe09f

default-extensions: remove GHC2021

update license: BSD3 -> MIT

Cabal flags

See merge request horizon/horizon-spec!3

Fix version

See merge request horizon/horizon-spec!2

Add CI

See merge request horizon/horizon-spec!1