Motivation for this change

New release https://github.com/moses-palmer/pystray/releases/tag/v0.16.0

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"

4 packages updated:
jellyfin-mpv-shim python27Packages.pystray (0.15.0 → 0.16.0) python37Packages.pystray (0.15.0 → 0.16.0) python38Packages.pystray (0.15.0 → 0.16.0)

4 packages built:
jellyfin-mpv-shim python27Packages.pystray python37Packages.pystray python38Packages.pystray

• 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)

/nix/store/rj6158nfn75byd49pznqmw2sqvkp5pwq-python3.8-pystray-0.15.0	  129790840
/nix/store/9b7cg0xnzy4swjydnp7dhvb31drzpbmw-python3.8-pystray-0.16.0	  129801328

• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.