tests/requirements.txt links to tests/requirements-2.12.txt, so
Kubespray uses ansible 2.12 by default for testing. However we
forgot to update testcases_prepare.sh to use ansible 2.12.
This updates testcases_prepare to use ansible 2.12.
* Ansible: separate requirements files for supported ansible versions
* Ansible: allow using ansible 2.11
* CI: Exercise Ansible 2.9 and Ansible 2.11 in a basic AIO CI job
* CI: Allow running a reset test outside of idempotency tests and running it in stage1
* CI: move ubuntu18-calico-aio job to stage2 and relay only on ubuntu20 with the variously supported ansible versions for stage1
* CI: add capability to install collections or roles from ansible-galaxy to mitigate missing behavior in older ansible versions
* Ansible: move to Ansible 3.4.0 which uses ansible-base 2.10.10
* Docs: add a note about ansible upgrade post 2.9.x
* CI: ensure ansible is removed before ansible 3.x is installed to avoid pip failures
* Ansible: use newer ansible-lint
* Fix ansible-lint 5.0.11 found issues
* syntax issues
* risky-file-permissions
* var-naming
* role-name
* molecule tests
* Mitogen: use 0.3.0rc1 which adds support for ansible 2.10+
* Pin ansible-base to 2.10.11 to get package fix on RHEL8
