Add Github Actions CI

Author: adisbladis

.github/workflows/nix-github-actions.yml

@@ -0,0 +1,25 @@
+name: Nix Flake actions
+
+on:
+  pull_request:
+  push:
+    branches:
+      - master
+      - main
+
+permissions:
+  contents: read
+  pages: write
+  id-token: write
+
+jobs:
+  nix-flake-check:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+      - uses: cachix/install-nix-action@v31
+        with:
+          github_access_token: ${{ secrets.GITHUB_TOKEN }}
+      - uses: cachix/cachix-action@v16
+      - name: Check flake
+        run: nix flake check -L -v