ocamlPackages.letsencrypt: 0.2.5 -> 0.3.0

[sternenseemann]

ocamlPackages.letsencrypt-dns: init at 0.3.0
ocamlPackages.letsencrypt-app: init at 0.2.5

https://github.com/mmaker/ocaml-letsencrypt/releases/tag/v0.3.0

Motivation for this change

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• 21.11 Release Notes (or backporting 21.05 Relase notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

[lukegb]

🐫

[vbgl]

This broke ocamlPackages.paf.

[sternenseemann]

You're right, we'll have to revert for now. For some reason even the nixpkgs-review local eval was convinced letsencrypt was a leaf package and didn't build any reverse deps, sorry about that.

I believe such cases should be avoided by #126934.