[19.09] Remove myself from maintainers on some packages

[ivan]

Motivation for this change

Removing myself from chromium, qolibri, and scream-receivers because I am not using much desktop Linux right now.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

[nixos-discourse]

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/packages-looking-for-a-maintainer/5442/2

[ivan]

cc @alexbakker - if you use scream-receivers, you may wish to add yourself to maintainers on master and release-19.09

qolibri is more obscure, it is possible no one is using it on NixOS, as I was unable to find a NixOS user going through https://github.com/ludios/qolibri/stargazers