nextcloud: 13.0.2 -> 13.0.3 (#41666)

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

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

These checks were done:

- built on NixOS

- 0 of 0 passed binary check by having a zero exit code.
- 0 of 0 passed binary check by having the new version present in output.
- found 13.0.3 with grep in /nix/store/hbps5w1zb88icnpqdpix29yx24hcf3ww-nextcloud-13.0.3
- directory tree listing: https://gist.github.com/feec7566b2d989d0e2f4a1870b1bb899
- du listing: https://gist.github.com/52d6f78c92d6b0bbd7179d3ed6da3d75