[CI] explicitly run unit tests (#54)

.github/workflows/integration-tests.yml

@@ -48,3 +48,12 @@ jobs:
           alias python='python3'
           cd python
           pip3 install -e '.[tests]'
+
+      - name: Run tests
+        run: |
+          cd python
+          LIT_TEST_DIR="build/$(ls build)/test"
+          if [ ! -d "$LIT_TEST_DIR" ]; then
+            echo "Not found `$LIT_TEST_DIR`.  Did you change an installation method?" ; exit -1
+          fi
+          lit -v "$LIT_TEST_DIR"