Add lower-constraints job to current development branch

The lower-constraints test was removed because of an issue where pip
could not correctly determine the required packages versions to install,
ending in an almost infinite loop that would end up in timeout, failure,
and general mayhem.
Recently the issue has been fixed and, if properly configured, the
lower-constraints test can provide good indication of which minimum
versions are required to support the current code.
This patch adds the test back to the current development branch, and it
runs only on master.
The lower-constraints file will stay in the future stable branches.

Fix olso.utils min requirement and remove doc8 from test-requirements
as it's already included in tox.ini config.

Change-Id: Ic0174f59b95a878539ab17f659f1663548e94ed7

lower-constraints.txt

@@ -0,0 +1,21 @@
+WebOb==1.7.1
+bcrypt==3.1.3
+coverage==4.0
+fixtures==3.0.0
+keystoneauth1==4.2.0
+keystonemiddleware==4.17.0
+openstacksdk==0.30.0
+os-service-types==1.2.0
+oslo.concurrency==3.26.0
+oslo.config==5.2.0
+oslo.i18n==3.15.3
+oslo.log==3.36.0
+oslo.messaging==5.29.0
+oslo.middleware==3.37.1
+oslo.service==1.24.0
+oslo.utils==3.34.0
+oslotest==3.2.0
+pbr==2.0.0
+stestr==1.0.0
+tenacity==6.2.0
+zeroconf==0.24.0

requirements.txt

@@ -6,7 +6,7 @@ pbr!=2.1.0,>=2.0.0 # Apache-2.0
 oslo.concurrency>=3.26.0 # Apache-2.0
 oslo.config>=5.2.0 # Apache-2.0
 oslo.i18n>=3.15.3 # Apache-2.0
-oslo.utils>=3.33.0 # Apache-2.0
+oslo.utils>=3.34.0 # Apache-2.0
 oslo.log>=3.36.0 # Apache-2.0
 zeroconf>=0.24.0 # LGPL
 bcrypt>=3.1.3 # Apache-2.0

test-requirements.txt

@@ -7,9 +7,6 @@ stestr>=1.0.0 # Apache-2.0
 oslotest>=3.2.0 # Apache-2.0
 fixtures>=3.0.0 # Apache-2.0/BSD
 
-# doc requirements
-doc8>=0.6.0 # Apache-2.0
-
 # used for JSON RPC unit tests
 keystonemiddleware>=4.17.0 # Apache-2.0
 oslo.messaging>=5.29.0 # Apache-2.0

zuul.d/project.yaml

@@ -2,6 +2,7 @@
     templates:
       - check-requirements
       - openstack-cover-jobs
+      - openstack-lower-constraints-master-branch-jobs
       - openstack-python3-xena-jobs
       - publish-openstack-docs-pti
     check: