.github: adding test action

Author: mrjbq7

.github/workflows/test.yml

@@ -0,0 +1,18 @@
+name: test
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: mlugg/setup-zig@v2
+        with:
+          version: master
+      - run: zig build test -freference-trace
+      - run: zig build -freference-trace