build(deps): bump nixbuild/nix-quick-install-action from 25 to 26

Bumps [nixbuild/nix-quick-install-action](https://github.com/nixbuild/nix-quick-install-action) from 25 to 26.
- [Release notes](https://github.com/nixbuild/nix-quick-install-action/releases)
- [Changelog](https://github.com/nixbuild/nix-quick-install-action/blob/master/RELEASE)
- [Commits](nixbuild/nix-quick-install-action@v25...v26)

---
updated-dependencies:
- dependency-name: nixbuild/nix-quick-install-action
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/nix-update.yml

@@ -8,7 +8,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
-      - uses: nixbuild/nix-quick-install-action@v25
+      - uses: nixbuild/nix-quick-install-action@v26
         with:
           nix_conf: |
             experimental-features = nix-command flakes