gsm: 1.0.17 -> 1.0.18

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

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

These checks were done:

- built on NixOS
- ran ‘/nix/store/99q2w40pn8n5mihvg5ar9jwlzafpp9gl-gsm-1.0.18/bin/toast -h’ got 0 exit code
- ran ‘/nix/store/99q2w40pn8n5mihvg5ar9jwlzafpp9gl-gsm-1.0.18/bin/toast help’ got 0 exit code
- ran ‘/nix/store/99q2w40pn8n5mihvg5ar9jwlzafpp9gl-gsm-1.0.18/bin/tcat -h’ got 0 exit code
- ran ‘/nix/store/99q2w40pn8n5mihvg5ar9jwlzafpp9gl-gsm-1.0.18/bin/tcat help’ got 0 exit code
- ran ‘/nix/store/99q2w40pn8n5mihvg5ar9jwlzafpp9gl-gsm-1.0.18/bin/untoast -h’ got 0 exit code
- ran ‘/nix/store/99q2w40pn8n5mihvg5ar9jwlzafpp9gl-gsm-1.0.18/bin/untoast help’ got 0 exit code
- found 1.0.18 with grep in /nix/store/99q2w40pn8n5mihvg5ar9jwlzafpp9gl-gsm-1.0.18
- directory tree listing: https://gist.github.com/af6b37d2f0a0b0757d66e91dce102967