Fix pytest unit test failure (#287)

Summary:
Pull Request resolved: #287

pytest-dev/pytest#3151

If there isn't a __init__.py file in a directory, pytest imports a test file into the global namespace. This means in a package structure not including __init__.py files, test files in separate directories with the same basename (filename not including directory) will overlap, and fortunately pytest fails with a visible error message rather than not executing the tests.

Reviewed By: Titousensei

Differential Revision: D14031515

fbshipit-source-id: dc0111b1fa62a630cf1be3da555632041ac7ba3c

pytext/data/test/__init__.py

@@ -0,0 +1,2 @@
+#!/usr/bin/env python3
+# Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved