fix(py-pytest-tornasync): add missing setuptools dependency

packages/py-pytest-tornasync/package.py

@@ -15,6 +15,7 @@ class PyPytestTornasync(PythonPackage):
     version("0.6.0.post2", sha256="d781b6d951a2e7c08843141d3ff583610b4ea86bfa847714c76edefb576bbe5d")
 
     depends_on('python@3.5:', type=('build', 'run'))
+    depends_on('py-setuptools', type=('build'))
     depends_on('py-pytest', type=('build', 'run'))
     depends_on('py-tornado@5.0:', type=('build', 'run'))