modify test-requirement according to requirements project

the OpenStack 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 project
Closes-Bug: #1666149

Change-Id: I97f1b58890f4205c5ba9387f3d55219ed2da8959

test-requirements.txt

@@ -2,7 +2,7 @@ hacking<0.11,>=0.10
 
 ansible-lint<=3.4.7
 jenkins-job-builder
-docutils>=0.11,!=0.13.1
-sphinx!=1.3b1,<1.4,>=1.2.1 # BSD
+docutils>=0.11
+sphinx>=1.5.1 # BSD
 oslosphinx>=4.7.0 # Apache-2.0
 reno>=1.8.0  # Apache-2.0