Drop RHEL 7 / CentOS 7 support and move to Python 3.8 minimum?

[Douglas Bagnall]

On 18/08/23 11:20, Andrew Bartlett via samba-technical wrote:

> We need to reduce our CI time, and one way to do that is to reuse
> objects as much as possible, creating read-only objects once per class,
> not per test.
> 
> This is much cleaner if with the addCleanup() and addClassCleanup()
> methods, so I would like to be able to do that.
> 
> To do that we need Python 3.8.  The primary blocker for this is the
> CentOS 7 build which uses Python 3.6 from EPEL, and a newer Python is
> not in that repo.

I had a look at the Python 3.8 git history for Lib/unittest to see if it 
would be simple to backport/recreate the ClassCleanup code into our 
TestCase wrappers (like we used to do for various assert methods), and 
the answer is NO. Thankfully.

I have no opinions about Centos 7, but I do agree that the supported 
Python versions need to be exactly determined by CI.

Douglas