atom: 1.25.1 -> 1.26.0

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

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

These checks were done:

- built on NixOS
- ran ‘/nix/store/q560gnycgnl44jmldg5y2a9akg47q8kb-atom-1.26.0/bin/apm -h’ got 0 exit code
- ran ‘/nix/store/q560gnycgnl44jmldg5y2a9akg47q8kb-atom-1.26.0/bin/apm --help’ got 0 exit code
- ran ‘/nix/store/q560gnycgnl44jmldg5y2a9akg47q8kb-atom-1.26.0/bin/apm help’ got 0 exit code
- ran ‘/nix/store/q560gnycgnl44jmldg5y2a9akg47q8kb-atom-1.26.0/bin/atom help’ got 0 exit code
- ran ‘/nix/store/q560gnycgnl44jmldg5y2a9akg47q8kb-atom-1.26.0/bin/.atom-wrapped help’ got 0 exit code
- found 1.26.0 with grep in /nix/store/q560gnycgnl44jmldg5y2a9akg47q8kb-atom-1.26.0
- directory tree listing: https://gist.github.com/10c433ad7807e5aeaa581f442b89dd6c