[release-23.05] forgejo: mark as insecure

[emilylange]

Description of changes

Abort eval with the following error (exact formatting from my terminal):

Known issues:
 - Forgejo's API and web endpoints before version 1.20.5-1 are affected by multiple
critical security vulnerabilities.

Non-exhaustive list:
 - reveal comments from issues and pull-requests from private repositories
 - delete comments from issues and pull-requests
 - get private release attachments
 - delete releases and tags
 - get ssh deployment keys (public key)
 - get OAuth2 applications (except for the secret)
 - 2FA not being enforced for the container registry login (docker login)

There isn't a clear way how to backport and validate all those fixes to the now EOL
forgejo 1.19.x and we, the forgejo nixpkgs maintainers, decided against bumping the
release from 1.19.x to 1.20.x due to its breaking nature.
Given nixpkgs 23.11 has been released by now and nixpkgs 23.05 will reach EOL very
soon (2023-12-31), please update to nixpkgs 23.11 instead.

Upstream: https://forgejo.org/2023-11-release-v1-20-5-1/

https://forgejo.org/2023-11-release-v1-20-5-1/

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 24.05 Release Notes (or backporting 23.05 and 23.11 Release 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.

[LeSuisse]

This feels reasonable to me, we do not have a lot of other choices anyway.

We probably should do the same for Gitea.