modify test-requirement according to requirements project

requirements project has modify version requirement of docutils/oslosphinx.
The link is below
https://review.openstack.org/#/c/418772/
So modify test-requirement like other projects
Closes-Bug: #1666149

Change-Id: I45653d9aa212da9c906accc56d501a4d066a6384

test-requirements.txt

@@ -4,11 +4,11 @@
 hacking<0.10,>=0.9.2
 
 coverage>=4.0 # Apache-2.0
-docutils!=0.13.1,>=0.11 # OSI-Approved Open Source, Public Domain
+docutils>=0.11 # OSI-Approved Open Source, Public Domain
 fixtures>=3.0.0 # Apache-2.0/BSD
 mock>=2.0 # BSD
 python-subunit>=0.0.18 # Apache-2.0/BSD
-sphinx!=1.3b1,<1.4,>=1.2.1 # BSD
+sphinx>=1.5.1 # BSD
 oslosphinx>=4.7.0 # Apache-2.0
 testrepository>=0.0.18 # Apache-2.0/BSD
 testscenarios>=0.4 # Apache-2.0/BSD