godot: 3.0.2 -> 3.0.3

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

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

These checks were done:

- built on NixOS
- Warning: no invocation of /nix/store/4hkbcbl0sgbd9npxsdf1qyn46k7npxgg-godot-3.0.3/bin/godot 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 3.0.3 with grep in /nix/store/4hkbcbl0sgbd9npxsdf1qyn46k7npxgg-godot-3.0.3
- directory tree listing: https://gist.github.com/ed73ee8e6d32a2bca8e7187447417b7e
- du listing: https://gist.github.com/25aba4f04e5002d49d3e5b12c3eed088