luaPackages.fzf-lua: fix flaky test

[midchildan]

Fix a flaky test in fzf-lua that's causing build failures.

https://hydra.nixos.org/build/292958691

I submitted a fix upstream in ibhagwan/fzf-lua#1914, but marked it as draft because it's yet to be seen if this will actually resolve the issue on Hydra.

I was able to fix the same error on my own GitHub Actions workflow though.

• Failing commit
• Fixed commit This just coincidentally passed because the overlay didn't properly apply to vimPlugins.fzf-lua due to multiple mistakes. Another fix did pass though, but this could be by coincidence too.

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/)
• 25.05 Release Notes (or backporting 24.11 and 25.05 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.

---

Add a 👍 reaction to pull requests you find important.

[awwpotato]

this pr and commit should be renamed to luaPackages.fzf-lua: fix flaky test, see commit conventions