Add workflow for testing nix flake

.github/workflows/nix.yml

@@ -0,0 +1,25 @@
+name: Nix
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    name: Nix Flake - Linux
+    permissions:
+      contents: read
+    steps:
+      - name: Install Nix
+        uses: cachix/install-nix-action@v13
+        with:
+          install_url: https://nixos-nix-install-tests.cachix.org/serve/i6laym9jw3wg9mw6ncyrk6gjx4l34vvx/install
+          install_options: '--tarball-url-prefix https://nixos-nix-install-tests.cachix.org/serve'
+          extra_nix_config: |
+            experimental-features = nix-command flakes
+            access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
+      - name: Clone project
+        uses: actions/checkout@v2
+      - name: Build
+        run: nix build --print-build-logs