Merge "Remove stestr from requirements.txt"

requirements.txt

@@ -11,4 +11,3 @@ setuptools!=24.0.0,!=34.0.0,!=34.0.1,!=34.0.2,!=34.0.3,!=34.1.0,!=34.1.1,!=34.2.
 PyYAML>=3.12 # MIT
 netaddr>=0.7.18 # BSD
 cryptography>=2.1 # BSD/Apache-2.0
-stestr>=2.0.0 # Apache-2.0