Bump the actions group with 1 update (#187)

Bumps the actions group with 1 update: [DeterminateSystems/nix-installer-action](https://github.com/determinatesystems/nix-installer-action).

- [Release notes](https://github.com/determinatesystems/nix-installer-action/releases)
- [Commits](DeterminateSystems/nix-installer-action@v5...v6)

---
updated-dependencies:
- dependency-name: DeterminateSystems/nix-installer-action
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: actions
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/flake_update.yml

@@ -18,7 +18,7 @@ jobs:
         with:
           submodules: true
       - name: Install Nix
-        uses: DeterminateSystems/nix-installer-action@v5
+        uses: DeterminateSystems/nix-installer-action@v6
       - name: Update flake.lock
         uses: DeterminateSystems/update-flake-lock@v20
         with: