Dropping lower constraints testing and remove py36,py37 support

We facing errors related to the new pip resolver, this
topic was discussed on the ML and QA team proposed to
to test lower-constraints [1].

I propose to drop this test because the complexity and recurring pain needed
to maintain that now exceeds the benefits provided by this mechanismes.

[1] http://lists.openstack.org/pipermail/openstack-discuss/2020-December/019390.html

Change-Id: Ie381bf7b8f4383072751b18d8cfa418e49409458

.zuul.yaml

@@ -1,7 +1,6 @@
 - project:
     templates:
       - check-requirements
-      - openstack-lower-constraints-jobs
-      - openstack-python3-wallaby-jobs
+      - openstack-python3-zed-jobs
       - publish-openstack-docs-pti
       - release-notes-jobs-python3

lower-constraints.txt

@@ -1,152 +0,0 @@
-alabaster==0.7.12
-alembic==1.0.7
-amqp==2.4.1
-appdirs==1.4.3
-asn1crypto==0.24.0
-astroid==1.3.8
-attrs==18.2.0
-Babel==2.3.4
-bandit==1.5.1
-bashate==0.5.1
-bcrypt==3.1.6
-botocore==1.12.87
-cachetools==3.1.0
-castellan==1.1.0
-certifi==2018.11.29
-cffi==1.14.0
-chardet==3.0.4
-Click==7.0
-cliff==2.14.0
-cmd2==0.9.7
-colorama==0.4.1
-coverage==4.0
-cryptography==2.5
-debtcollector==1.20.0
-decorator==4.3.2
-doc8==0.6.0
-docutils==0.14
-dogpile.cache==0.6.8
-dulwich==0.19.10
-eventlet==0.26.0
-extras==1.0.0
-fasteners==0.14.1
-fixtures==3.0.0
-Flask==1.0.2
-future==0.16.0
-futurist==1.8.0
-gitdb2==2.0.5
-GitPython==2.1.11
-greenlet==0.4.15
-grpcio==1.24.3
-imagesize==1.1.0
-iso8601==0.1.12
-itsdangerous==1.1.0
-Jinja2==2.10
-jmespath==0.9.3
-jsonpatch==1.23
-jsonpointer==2.0
-jsonschema==2.6.0
-keystoneauth1==3.11.2
-keystonemiddleware==5.3.0
-kombu==5.0.2
-linecache2==1.0.0
-logilab-common==1.4.2
-Mako==1.0.7
-MarkupSafe==1.1.0
-microversion-parse==0.2.1
-monotonic==1.5
-mox3==0.26.0
-msgpack==0.6.1
-msgpack-python==0.5.6
-munch==2.3.2
-netaddr==0.7.19
-netifaces==0.10.9
-openstacksdk==0.24.0
-os-api-ref==1.6.0
-os-client-config==1.31.2
-os-service-types==1.5.0
-osc-lib==1.12.0
-oslo.cache==1.32.0
-oslo.concurrency==3.29.0
-oslo.config==6.8.0
-oslo.context==2.22.0
-oslo.db==6.0.0
-oslo.i18n==3.15.3
-oslo.log==3.36.0
-oslo.messaging==9.4.0
-oslo.middleware==3.37.0
-oslo.policy==2.1.0
-oslo.rootwrap==5.15.1
-oslo.serialization==2.18.0
-oslo.service==1.36.0
-oslo.upgradecheck==0.1.1
-oslo.utils==3.33.0
-oslotest==3.2.0
-packaging==19.0
-paramiko==2.7.1
-Paste==3.0.6
-PasteDeploy==2.0.1
-pbr==2.0.0
-prettytable==0.7.2
-pyasn1==0.4.5
-pycadf==2.9.0
-pycodestyle==2.0.0
-pycparser==2.19
-Pygments==2.3.1
-pyinotify==0.9.6
-pylint==1.4.5
-PyNaCl==1.3.0
-pyOpenSSL==19.0.0
-pyparsing==2.3.1
-pyperclip==1.7.0
-python-barbicanclient==4.8.1
-python-cinderclient==4.1.0
-python-dateutil==2.8.0
-python-editor==1.0.4
-python-glanceclient==2.15.0
-python-heatclient==1.17.0
-python-keystoneclient==3.18.0
-python-manilaclient==1.26.0
-python-mimeparse==1.6.0
-python-neutronclient==6.11.0
-python-novaclient==11.1.0
-python-pcre==0.7
-python-subunit==1.4.0
-python-swiftclient==3.6.0
-pytz==2018.9
-PyYAML==3.13
-repoze.lru==0.7
-requests==2.14.2
-requestsexceptions==1.4.0
-restructuredtext-lint==1.2.2
-rfc3986==1.2.0
-Routes==2.4.1
-sahara==10.0.0.0b1
-simplejson==3.16.0
-six==1.10.0
-smmap2==2.0.5
-snowballstemmer==1.2.1
-SQLAlchemy==1.2.17
-sqlalchemy-migrate==0.13.0
-sqlparse==0.2.4
-statsd==3.3.0
-stestr==1.0.0
-stevedore==1.30.0
-Tempita==0.5.2
-tenacity==6.1.0
-testrepository==0.0.20
-testresources==2.0.1
-testscenarios==0.4
-testtools==2.4.0
-tooz==1.65.0
-traceback2==1.4.0
-unittest2==1.1.0
-urllib3==1.24.1
-vine==1.2.0
-voluptuous==0.11.5
-warlock==1.3.0
-wcwidth==0.1.7
-WebOb==1.8.5
-Werkzeug==0.14.1
-whereto==0.4.0
-wrapt==1.11.1

setup.cfg

@@ -3,15 +3,14 @@ name = sahara-plugin-vanilla
 summary = Vanilla Plugin for Sahara Project
 description-file = README.rst
 license = Apache Software License
-python-requires = >=3.6
+python-requires = >=3.8
 classifiers =
     Programming Language :: Python
     Programming Language :: Python :: Implementation :: CPython
     Programming Language :: Python :: 3 :: Only
     Programming Language :: Python :: 3
-    Programming Language :: Python :: 3.6
-    Programming Language :: Python :: 3.7
     Programming Language :: Python :: 3.8
+    Programming Language :: Python :: 3.9
     Environment :: OpenStack
     Intended Audience :: Information Technology
     Intended Audience :: System Administrators

tox.ini

@@ -96,10 +96,3 @@ enable-extensions=H904,H106,H203,H204,H205
 # [W503] Line break occurred before a binary operator
 # [W504] line break after binary operator
 ignore=E123,E226,E402,E731,W503,W504
-
-[testenv:lower-constraints]
-deps =
-  -c{toxinidir}/lower-constraints.txt
-  -r{toxinidir}/test-requirements.txt
-  -r{toxinidir}/requirements.txt
-  -r{toxinidir}/doc/requirements.txt