ci: init github ci

Author: steve-chavez

.github/workflows/ci.yaml

@@ -0,0 +1,32 @@
+name: CI
+
+on: [push, pull_request]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        pg-version: ['14', '15', '16', '17', '18']
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Nix
+        uses: cachix/install-nix-action@v30
+        with:
+          nix_path: nixpkgs=channel:nixos-unstable
+
+      - name: Use Cachix Cache
+        uses: cachix/cachix-action@v10
+        with:
+          name: nxpg
+          authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
+
+      - name: Run tests
+        run: nix-shell --run "xpg -v ${{ matrix.pg-version }} test"
+
+      - if: ${{ failure() }}
+        run: |
+          cat regression.out
+          cat regression.diffs