Bump cachix/install-nix-action from 20 to 23 in /.github/workflows

Bumps [cachix/install-nix-action](https://github.com/cachix/install-nix-action) from 20 to 23.
- [Release notes](https://github.com/cachix/install-nix-action/releases)
- [Commits](cachix/install-nix-action@v20...v23)

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

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

.github/workflows/test.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v4
-    - uses: cachix/install-nix-action@v20
+    - uses: cachix/install-nix-action@v23
       with:
         nix_path: nixpkgs=channel:nixos-unstable
         extra_nix_config: "system-features = nixos-test benchmark big-parallel kvm"

.github/workflows/update-nixos-23.05.yaml

@@ -10,7 +10,7 @@ jobs:
     - name: Get date
       run: echo "BRANCH_NAME=nixpkgs-update-$(date +'%Y-%m-%dT%H%M%S')" >> $GITHUB_ENV
     - uses: actions/checkout@v4
-    - uses: cachix/install-nix-action@v20
+    - uses: cachix/install-nix-action@v23
       with:
         nix_path: nixpkgs=channel:nixos-unstable
         extra_nix_config: |