fix sentence_transformers segfault in integration tests

[hwchase17]

per https://github.com/hwchase17/langchain/issues/104 needed to start skipping unit tests due to a segfault - look into this more and figure out what fixes are needed https://github.com/hwchase17/langchain/blob/95dd2f140e19d29bdb62d4dae2048e3edf0ee147/tests/integration_tests/embeddings/test_huggingface.py#L7