CI: add workflow for testing website build on PRs

Author: mlugg

.github/workflows/test-website.yml

@@ -0,0 +1,17 @@
+name: Test Website
+
+on:
+  pull_request:
+jobs:
+  build:
+    name: Build
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v4
+
+      - name: Setup Zig Compiler
+        uses: mlugg/setup-zig@v2
+
+      - name: Build the website
+        run: zig build --summary new