add spec tests to ci

.github/workflows/ci.yml

@@ -0,0 +1,17 @@
+name: Spec tests
+
+on: [pull_request]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v3
+      - name: Set up Python 3.x
+        uses: actions/setup-python@v4
+        with:
+          # Semantic version range syntax or exact version of a Python version
+          python-version: '3.x'
+      - name: Run tests
+        run: cd carnot && python -m unittest