Unbreak Github Actions based on the work in crypto policies role

[Jakuje]

• Remove CentOS 6 build as it seems to be broken
• Add CentOS 8 image
• Remove ansible 2.7 as ansible-lint is no longer installable with it
• Build also on push to generate the build status icons in readme
• Use Python 3 packages with DNF for CentOS 8

https://github.com/linux-system-roles/crypto_policies/pull/4/

[natoscott]

* Remove CentOS 6 build as it seems to be broken

CentOS 6 has recently reached EOL. It is possible to keep things working (if desired here?) - for CI on the PCP project used by the metrics role, this set of instructions proved very useful: https://arstech.net/centos-6-error-yumrepo-error-all-mirror-urls-are-not-using-ftp-http/

[Jakuje]

* Remove CentOS 6 build as it seems to be broken

CentOS 6 has recently reached EOL. It is possible to keep things working (if desired here?) - for CI on the PCP project used by the metrics role, this set of instructions proved very useful:

For crypto policies, it was an easy question as it runs only on RHEL8 so removing RHEL6 was obvious solution. I understand it might be useful for other roles, bu at this moment it is broken so I did not see a reason why to keep it failing all pipelines. I don't have any at this moment that would work with RHEL6 so I would keep this part for others.

https://arstech.net/centos-6-error-yumrepo-error-all-mirror-urls-are-not-using-ftp-http/

This link does not work for me.

[richm]

This is mostly fixed by https://github.com/linux-system-roles/template/pull/59 We'll remove support for ansible 2.7 in a separate commit, but for now, the current code removes the problem that we had with ansible 2.7 I suppose we could still use the - push from this PR

[Jakuje]

Right. I tried to rebase this on top of current version and the only thing that was left was the on:push part. I think that one is certainly useful to get some results in the README. Now, it just says "tox: no status", which is not very helpful.