Bump nixbuild/nix-quick-install-action from 14 to 15

Bumps [nixbuild/nix-quick-install-action](https://github.com/nixbuild/nix-quick-install-action) from 14 to 15.
- [Release notes](https://github.com/nixbuild/nix-quick-install-action/releases)
- [Changelog](https://github.com/nixbuild/nix-quick-install-action/blob/master/RELEASE)
- [Commits](https://github.com/nixbuild/nix-quick-install-action/compare/v14...v15)

---
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/build.yml

@@ -56,7 +56,7 @@ jobs:
       run: yarn
 
     - name: Install Nix
-      uses: nixbuild/nix-quick-install-action@v14
+      uses: nixbuild/nix-quick-install-action@v15
 
     - name: Setup Cachix
       if: github.event_name == 'push' && github.repository_owner == 'stephank'