matrix-tuwunel: disable check phase on aarch64

[scvalex]

The tuwunel build on aarch64 is timing out in Hydra. Everything is fine on x86-64 in Hydra or when I build locally on aarch64.

This regression was likely introduced during the 1.7.0 version bump in #525790.

Pretty much the only thing that could be timing out in the build are the "smoke tests" that actually start the full server during cargo test. So, let's try disabling check phase on aarch64.

I'm not happy with disabling tests like this, but I don't know how to debug this since I can't reproduce it locally. I'd argue this is fine because the tests are still being run by Hydra on x86-64 and we'll still be running our own NixOS tests on all platforms which also exercise the server.

Things done

• Built on platform:
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• Tested, as applicable:
  • NixOS tests in nixos/tests.
  • Package tests at passthru.tests.
  • Tests in lib/tests or pkgs/test for functions and "core" functionality.
• Ran nixpkgs-review on this PR. See nixpkgs-review usage.
• Tested basic functionality of all binary files, usually in ./result/bin/.
• Nixpkgs Release Notes
  • Package update: when the change is major or breaking.
• NixOS Release Notes
  • Module addition: when adding a new NixOS module.
  • Module update: when the change is significant.
• Fits CONTRIBUTING.md, pkgs/README.md, maintainers/README.md and other READMEs.
• Follows the automation/AI policy.

[PedroHLC]

Maybe all aarch64

[scvalex]

Maybe all aarch64

Good point. Done.