add gh action

.github/workflows/ci.yml

@@ -0,0 +1,18 @@
+name: "CI"
+
+on:
+  push:
+    branches: ["main"]
+  pull_request:
+    branches: ["main"]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: cachix/install-nix-action@v22
+        with:
+          github_access_token: ${{ secrets.GITHUB_TOKEN }}
+      - run: nix build
+      - run: nix flake check

flake.nix

@@ -58,9 +58,11 @@
           };
 
           default = packages.all;
+          override = packages.all;
+          overrideDerivation = packages.all;
         };
 
-        devShell = pkgs.mkShell {
+        devShells.default = pkgs.mkShell {
           buildInputs = with pkgs;
             [
               # Rust