[new release] opam-monorepo (0.4.0)

CHANGES:

### Added

- Display warning when a package to be locked is missing a `dev-repo` field and
  is being skipped because of it (tarides/opam-monorepo#341, tarides/opam-monorepo#362, @kit-ty-kate, @Leonidas-from-XIV)
- Add option `--keep-symlinked-dir` to preserve symlinks in `duniverse/`, which
  can be useful for local development. (tarides/opam-monorepo#348, tarides/opam-monorepo#366, @hannesm,
  @Leonidas-from-XIV)
- Adopt the OCaml Code of Conduct (tarides/opam-monorepo#391, @rikusilvola)
- Add solver tests (tarides/opam-monorepo#394, @samoht)

### Changed

- Canonicalize the URLs of the OPAM `dev-repo` fields to be able to detect more
  semantically equivalent URLs, this should reduce the risk of build failures
  due to duplicate code pulled (tarides/opam-monorepo#118, tarides/opam-monorepo#365 @TheLortex, @Leonidas-from-XIV)

- Simple the error message printed when dependencies don't use dune as their
  build system. The opam-0install diagnostic message is no longer printed in
  this case and the message has been reformatted and reworded to make the
  salient information easier to see. (tarides/opam-monorepo#384, @gridbugs)

- Encode `dev-repo` constraints in the opam solver - this allows to resolve
  more involved version constraints that were failing before (tarides/opam-monorepo#396, @samoht)

### Deprecated

### Fixed

- Error in case where multiple packages with different dev-repo fields would be
  placed in the same duniverse directory (tarides/opam-monorepo#377, @gridbugs)

- Fix a failure when using opam-monorepo with an opam 2.2 root
  (tarides/opam-monorepo#379, @kit-ty-kate)

- Fix assertion failure when prefix of "lock" subcommand is used (tarides/opam-monorepo#381,
  @gridbugs)

- Treat packages without build commands as virtual only if also lack install
  commands, as some non-virtual packages might only have install commands.
  (tarides/opam-monorepo#376 @Leonidas-from-XIV, @gridbugs)

- Improve the ordering of package candidates by putting broken packages at
  then end of the list (tarides/opam-monorepo#395, tarides/opam-monorepo#397, @samoht)

### Removed

### Security

packages/opam-monorepo/opam-monorepo.0.4.0/opam

@@ -0,0 +1,54 @@
+opam-version: "2.0"
+synopsis: "Assemble and manage fully vendored Dune repositories"
+description: """
+The opam monorepo plugin provides a convenient interface to bridge the
+opam package manager with having a local copy of all the source
+code required to build a project using the dune build tool."""
+maintainer: ["anil@recoil.org"]
+authors: [
+  "Anil Madhavapeddy" "Nathan Rebours" "Lucas Pluvinage" "Jules Aguillon"
+]
+license: "ISC"
+homepage: "https://github.com/tarides/opam-monorepo"
+doc: "https://tarides.github.io/opam-monorepo"
+bug-reports: "https://github.com/tarides/opam-monorepo/issues"
+depends: [
+  "dune" {>= "3.6"}
+  "ocaml" {>= "4.10.0"}
+  "odoc" {with-doc}
+]
+conflicts: [
+  "dune-build-info" {= "2.7.0" | = "2.7.1"}
+  "dune-configurator" {= "2.7.0" | = "2.7.1"}
+]
+dev-repo: "git+https://github.com/tarides/opam-monorepo.git"
+build: [ "dune" "build" "-p" name "-j" jobs "@install" "@test/lib/runtest" {with-test} ]
+flags: [ plugin ]
+depexts: [
+  ["devel/pkgconf"] {os = "openbsd"}
+  ["pkg-config"] {os-family = "debian"}
+  ["pkg-config"] {os = "macos" & os-distribution = "homebrew"}
+  ["pkgconf"] {os = "freebsd"}
+  ["pkgconf"] {os-distribution = "alpine"}
+  ["pkgconf"] {os-distribution = "arch"}
+  ["pkgconf-pkg-config"] {os-distribution = "fedora"}
+  ["pkgconf-pkg-config"] {os-distribution = "mageia"}
+  ["pkgconf-pkg-config"] {os-distribution = "centos" & os-version >= "8"}
+  ["pkgconf-pkg-config"] {os-distribution = "ol" & os-version >= "8"}
+  ["pkgconf-pkg-config"] {os-distribution = "rhel" & os-version >= "8"}
+  ["pkgconfig"] {os-distribution = "nixos"}
+  ["pkgconfig"] {os = "macos" & os-distribution = "macports"}
+  ["pkgconfig"] {os-distribution = "centos" & os-version <= "7"}
+  ["pkgconfig"] {os-distribution = "ol" & os-version <= "7"}
+  ["pkgconfig"] {os-distribution = "rhel" & os-version <= "7"}
+  ["system:pkgconf"] {os = "win32" & os-distribution = "cygwinports"}
+]
+url {
+  src:
+    "https://github.com/tarides/opam-monorepo/releases/download/0.4.0/opam-monorepo-0.4.0.tbz"
+  checksum: [
+    "sha256=5fac86370f4b002410081ab1190abe23a542fb146dc73d927895eaa0c2c6eac2"
+    "sha512=ced42bab2ce2bdf1d832dae06f472eb8bf18c7c41bab7d77ec13f663e2fd69ad5602e45145e952f8f1f72613cac9c6a8ad6e2f43f5f58265374df9247a015c53"
+  ]
+}
+x-commit-hash: "2798f4622337a62a645bf835226f6fbfd8ab3d2c"