Drop py36 and py37 from zuul gate test

These are not supported anymore from temptest.

Change-Id: I4b622289291f175471d050e856b22fe3117ebadc
(cherry picked from commit eb89f3f56d)

.zuul.yaml

@@ -1,19 +1,13 @@
 - project:
     templates:
       - openstack-lower-constraints-jobs
-      - openstack-python3-victoria-jobs
-      - check-requirements
       - openstack-cover-jobs
     check:
       jobs:
         - openstack-tox-pep8
-        - openstack-tox-py36
-        - openstack-tox-py37
         - openstack-tox-py38
         - openstack-tox-lower-constraints
     gate:
       jobs:
         - openstack-tox-pep8
-        - openstack-tox-py36
-        - openstack-tox-py37
         - openstack-tox-py38

lower-constraints.txt

@@ -8,7 +8,7 @@ hacking>=3.0.1 # Apache-2.0
 netaddr==0.7.18
 openstackdocstheme==1.18.1
 oslo.i18n==3.20.0
-oslo.log==4.2.1
+oslo.log==4.6.0
 oslo.serialization==2.28.1
 oslo.service==1.31.0
 oslo.utils==4.4.0

requirements.txt

@@ -9,7 +9,9 @@ eventlet>=0.24.1 # MIT
 netaddr>=0.7.18 # BSD
 tenacity>=6.0.0 # Apache-2.0
 oslo.i18n>=3.20.0 # Apache-2.0
-oslo.log>=4.2.1 # Apache-2.0
+oslo.log>=4.2.1;python_version=='3.6'
+oslo.log>=4.2.1;python_version=='3.7'
+oslo.log>=4.6.0;python_version=='3.8'
 oslo.serialization>=2.28.1 # Apache-2.0
 oslo.service>=1.31.0 # Apache-2.0
 oslo.utils>=4.4.0 # Apache-2.0