itk: unstable -> 5.3.0

[bcdarwin]

Description of changes

Previously we had itk 5.2.1 and itk-unstable tracking the 5.3 branch (used only by the ANTs package). Due to the ITK 5.3.0 release, this PR replaces itk-unstable with 5.3.0 and makes it the default and renames 5.2.1 to itk_5_2. Even though only one package has so far switched to it out of the 5 or so packages depending on ITK directly, it seems to make 5.3.x the default in the interest of forward compatibility (VTK in Nixpkgs made the opposite decision and it's been annoying to get things updated, although perhaps not for technical reasons).

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• 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/)
• 23.05 Release Notes (or backporting 22.11 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
  • (Release notes changes) Ran nixos/doc/manual/md-to-db.sh to update generated release notes
• Fits CONTRIBUTING.md.

[Mindavi]

@ofborg build c3d elastix simpleitk itk_5_2

[bcdarwin]

@ofborg build ants