feat: update GitHub actions workflow to use new actions

Author: Rishab Garg

.github/workflows/main.yml

@@ -11,6 +11,9 @@ jobs:
       id-token: write
       contents: read
     steps:
-      - uses: actions/checkout@v5.0.0
-      - uses: DeterminateSystems/determinate-nix-action@main # or v3.11.2 to pin to a release
-      - run: nix build .
+      - uses: actions/checkout@v4
+      - uses: DeterminateSystems/nix-installer-action@main
+      - uses: DeterminateSystems/magic-nix-cache-action@main
+      - uses: DeterminateSystems/flake-checker-action@main
+      - name: Run `nix build`
+        run: nix build .