krita: 4.0.2 -> 4.0.3

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

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

These checks were done:

- built on NixOS
- Warning: no invocation of /nix/store/603q26b9pswma12ypz68l39jqyrxbvvy-krita-4.0.3/bin/krita 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 4.0.3 with grep in /nix/store/603q26b9pswma12ypz68l39jqyrxbvvy-krita-4.0.3
- directory tree listing: https://gist.github.com/23ba1bbd1767e4a61fafcd9646d63898
- du listing: https://gist.github.com/4eed85b1634be0fb42b59cdc55799267