run tests during ci

.github/workflows/build.yml

@@ -50,6 +50,10 @@ jobs:
     - name: Pre-commit hooks
       run: |
         pre-commit run --all-files
+    - name: Run tests
+      run: |
+        cd tests/ && python -m unittest discover
+        cd ..
     - name: Build assets
       run: circuitpython-build-bundles --filename_prefix ${{ steps.repo-name.outputs.repo-name }} --library_location .
     - name: Archive bundles