updated tox file (#11087)

Co-authored-by: Laurent Mazuel <[email protected]>

Author: Srinath Narayanan

sdk/cosmos/azure-cosmos/tox.ini

@@ -7,7 +7,8 @@
 envlist = py27, py34
 
 [base]
-deps = pytest, -rdev_requirements.txt
+deps = pytest
+       -rdev_requirements.txt
 
 [pytest]
 python_files=test/**.py