[goal] Migrate patrole jobs to focal

As per victoria cycle testing runtime and community goal[1]
we need to migrate upstream CI/CD to Ubuntu Focal(20.04).

Most of the Tempest jobs will be migrate automatically once devstack
base job start running on Focal(Depends-On).

stable jobs testing stable branch needs to keep running on their supported
distro version which is bionic from stein till ussuri.

Also fixing few lower constraints.

[1] https://governance.openstack.org/tc/goals/selected/victoria/migrate-ci-cd-jobs-to-ubuntu-focal.html

Change-Id: Id1799fee94071c2eaea17bc50ef2845a8489fa92

.zuul.yaml

@@ -96,11 +96,13 @@
 - job:
     name: patrole-member-ussuri
     parent: patrole-member
+    nodeset: openstack-single-node-bionic
     override-checkout: stable/ussuri
 
 - job:
     name: patrole-member-train
     parent: patrole-member
+    nodeset: openstack-single-node-bionic
     override-checkout: stable/train
     vars:
       devstack_localrc:
@@ -109,6 +111,7 @@
 - job:
     name: patrole-member-stein
     parent: patrole-member
+    nodeset: openstack-single-node-bionic
     override-checkout: stable/stein
     vars:
       devstack_localrc:

lower-constraints.txt

@@ -4,7 +4,7 @@ asn1crypto==0.24.0
 Babel==2.5.3
 bcrypt==3.1.4
 certifi==2018.1.18
-cffi==1.11.5
+cffi==1.14.0
 chardet==3.0.4
 cliff==2.11.0
 cmd2==0.8.1
@@ -58,7 +58,7 @@ python-dateutil==2.7.0
 python-mimeparse==1.6.0
 python-subunit==1.2.0
 pytz==2018.3
-PyYAML==3.12
+PyYAML==3.13
 requests==2.18.4
 requestsexceptions==1.4.0
 rfc3986==1.1.0