itk: 4.12.2 -> 4.13.0

Semi-automatic update generated by https://github.com/ryantm/nixpkgs-update tools.

This update was made based on information from https://repology.org/metapackage/itk/versions.

These checks were done:

- built on NixOS
- Warning: no binary found that responded to help or version flags. (This warning appears even if the package isn't expected to have binaries.)
- found 4.13.0 with grep in /nix/store/9dfpbhp02y597y9zw3xvdcjsb8w3gqjv-itk-4.13.0
- directory tree listing: https://gist.github.com/4a6da5cc90a5718caa480eba957def8f