signal-desktop-beta: only build on x86_64-linux

[teutat3s]

Description of changes

Build for aarch64-linux is currently failing since forever.

Upstream does not provide packages for aarch64-linux:

Note that these instructions only work for 64 bit Debian-based Linux
distributions

Source: https://support.signal.org/hc/en-us/articles/360007318471-Signal-Beta

• Formatted using nixfmt-rfc-style

ZHF: #309482

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 24.05 Release Notes (or backporting 23.05 and 23.11 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

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[DontEatOreo]

Relevant: #286188

Currently that PR is also modifying the pkgs/applications/networking/instant-messengers/signal-desktop/default.nix

[DontEatOreo]

I think we should wait for #286188 to be merged before doing anything here as we're still forming a consensus on the pkgs/applications/networking/instant-messengers/signal-desktop/default.nix

[teutat3s]

@ofborg eval

[kirillrdy]

@teutat3s you should be using nixfmt-rfc-style for formatting

[teutat3s]

@kirillrdy Done.

[teutat3s]

In my opinion, this change does not interfere with the other mentioned PR and can be reviewed and merged independently.

[DontEatOreo]

How so? Both PRs modify the same file. Since #286188 was created first and there is already a discussion about how to deal with the file this PR is trying to modify, I think it will be better to wait and see what consensus will be reached, so later this PR can be rebased and follow that consensus

[wegank]

That PR seems to be stalled and needs to be rebased anyway...