ci: use nix-installer-action

Also use magic-nix-cache-action@main

Closes: #4

Author: m15a

.github/workflows/ci.yml

@@ -11,9 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - uses: cachix/install-nix-action@v26
-        with:
-          github_access_token: ${{ secrets.GITHUB_TOKEN }}
-      - uses: DeterminateSystems/magic-nix-cache-action@v4
+      - uses: DeterminateSystems/nix-installer-action@main
+      - uses: DeterminateSystems/magic-nix-cache-action@main
       - run: |
           nix flake check