replace CI, just Nix now

Author: raehik

.github/workflows/ci.yml

@@ -0,0 +1,22 @@
+name: Nix
+
+on:
+  push:
+
+jobs:
+  nix-build:
+    name: nix build .#${{ matrix.ghc }}-strongweak
+    strategy:
+      fail-fast: false
+      matrix:
+        ghc: [ghc98, ghc910]
+    runs-on: ubuntu-latest
+    permissions:
+      id-token: "write"
+      contents: "read"
+    steps:
+    - uses: actions/checkout@v4
+    - uses: DeterminateSystems/nix-installer-action@main
+    - uses: DeterminateSystems/magic-nix-cache-action@main
+    - uses: DeterminateSystems/flake-checker-action@main
+    - run: nix build .#${{ matrix.ghc }}-strongweak