Run lower-constraints on Bionic and update python-keystoneclient

This commit updates the version of python-keystoneclient to 3.10.0,
which has fixes to handle different openssl versions:

  https://review.openstack.org/#/c/406175/2

Since we're bumping the minimum version of python-keystoneclient to
include that fix, we can safely run lower-constraints on Bionic
instead of Xenial.

Change-Id: I52fa44fe76590aced193618406ad30eb70d04f9d

.zuul.yaml

@@ -1,11 +1,7 @@
-- job:
-    name: openstack-tox-lower-constraints-keystone-xenial
-    parent: openstack-tox-lower-constraints
-    nodeset: openstack-single-node-xenial
-
 - project:
     templates:
       - openstack-cover-jobs
+      - openstack-lower-constraints-jobs
       - openstack-python-jobs
       - openstack-python36-jobs
       - openstack-python37-jobs
@@ -14,10 +10,3 @@
       - lib-forward-testing
       - lib-forward-testing-python3
       - release-notes-jobs-python3
-    check:
-      jobs:
-        - openstack-tox-lower-constraints-keystone-xenial
-    gate:
-      jobs:
-        - openstack-tox-lower-constraints-keystone-xenial
-

lower-constraints.txt

@@ -57,7 +57,7 @@ pyinotify==0.9.6
 pyparsing==2.2.0
 pyperclip==1.6.0
 python-dateutil==2.7.0
-python-keystoneclient==3.8.0
+python-keystoneclient==3.10.0
 python-memcached==1.56
 python-mimeparse==1.6.0
 python-subunit==1.2.0

requirements.txt

@@ -12,7 +12,7 @@ oslo.serialization!=2.19.1,>=2.18.0 # Apache-2.0
 oslo.utils>=3.33.0 # Apache-2.0
 pbr!=2.1.0,>=2.0.0 # Apache-2.0
 pycadf!=2.0.0,>=1.1.0 # Apache-2.0
-python-keystoneclient>=3.8.0 # Apache-2.0
+python-keystoneclient>=3.10.0 # Apache-2.0
 requests>=2.14.2 # Apache-2.0
 six>=1.10.0 # MIT
 WebOb>=1.7.1 # MIT