lua51Packages.lgi: 0.9.1 -> 0.9.2

Semi-automatic update generated by https://github.com/ryantm/nix-update tools. These checks were done:

- built on NixOS
- Warning: no binary found that responded to help or version flags. (This warning appears even if the package isn't expected to have binaries.)
- found 0.9.2 with grep in /nix/store/q6lcshhmi0dn8ndz2jz9nlircfww4fcm-lgi-0.9.2
- directory tree listing: https://gist.github.com/48d4d638fbd1169b1c96b7e506202b93