appstream-glib: 0.7.8 -> 0.7.9

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

This update was made based on information from https://repology.org/metapackage/appstream-glib/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 0.7.9 with grep in /nix/store/c15qrflgi7dn8by6lndn4szzxqfv6fbh-appstream-glib-0.7.9
- directory tree listing: https://gist.github.com/8232c1c6ab5664cb630765eefbbf7f5f
- du listing: https://gist.github.com/820804a1f32be45fb3ccdd98d6dd6a86