marp: 0.0.12 -> 0.0.13

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

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

These checks were done:

- built on NixOS
- Warning: no invocation of /nix/store/xyisjivarv9zwlwh6nm0i55njfw7dkss-marp-0.0.13/bin/Marp had a zero exit code or showed the expected version
- 0 of 1 passed binary check by having a zero exit code.
- 0 of 1 passed binary check by having the new version present in output.
- found 0.0.13 with grep in /nix/store/xyisjivarv9zwlwh6nm0i55njfw7dkss-marp-0.0.13
- directory tree listing: https://gist.github.com/d9ae780141c62a0f06dfa28225d45e9a
- du listing: https://gist.github.com/2b208d562d59a7343631492d214dbfd1