Summary: Added as a submodule since it's our private fork.

Test Plan:
```
cd throwaway
bazel build :pypa_demo
../bazel-bin/throwaway/pypa_demo <python file>
```

Reviewers: #engineering, michelle

Reviewed By: #engineering, michelle

Differential Revision: https://phab.corp.pixielabs.ai/D194

GitOrigin-RevId: bc1ba537d08dac4c996c58dd7504a4668668733a