Need tests for examples

[masenf]

As noted in https://github.com/pynecone-io/pynecone/pull/856#issuecomment-1518772949, we should consider adding tests for the example projects.

At the very least, we should be able to pc init and pc export every project without errors.

Down the road it would be amazing to have a pytest-pynecone plugin that would help developers test their full stack apps end-to-end.