Update lix stable: 2.91 -> 2.93

[dot-file]

pkgs.lix and pkgs.lixPackageSets.stable.lix point to lix_2_91 even though the latest version is lix_2_93.
In the derivation there's a comment that says:

  # Note: This is not yet 2.92 because of a non-deterministic `curl` error.
  # See: https://git.lix.systems/lix-project/lix/issues/662
  stable = self.lix_2_91;

However the curl issue that made 2.92 and up unstable has been solved:

• https://git.lix.systems/lix-project/lix/issues/662#issuecomment-10236
• curl: 8.12.1 -> 8.13.0 #396200

So I made "stable" point to lix_2_93 instead.

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.

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[lf-]

the only things I'm aware of that are worse on 2.93 are cache query perf and we fixed that in 2.94 (upcoming). let's send it.

[lf-]

your commit message however is not compliant, please fix it before we can merge. "lixPackageSets.stable: 2.91 -> 2.93" or something like that.

[dot-file]

your commit message however is not compliant, please fix it before we can merge.

Done