slack: 4.15.0 -> 4.16.0

[JesusMtnez]

Motivation for this change

Update slack to 4.16.0

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"
• 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.

[r-rmcgibbo]

Result of nixpkgs-review pr 123646 at f6dfcbc run on x86_64-linux 1

2 packages built successfully:

• slack
• tests.trivial

1 suggestion:

• warning: missing-phase-hooks

  installPhase should probably contain runHook preInstall and runHook postInstall.

  Near pkgs/applications/networking/instant-messengers/slack/default.nix:136:5:

      |
  136 |     installPhase = ''
      |     ^