Address CG issue in SLES 12 image

[dougbu]

SLES 12 got left behind when we fixed dotnet/arcade#13186 in !32218. We need to continue work to

1. Find a way to bump the offending package version on the legacy machine
2. Remove this platform from our queues if we're unable to complete (1)
3. Get an exception for the CG issue — after we've exhausted other options

Release Note Category

• Feature changes/additions
• Bug fixes
• Internal Infrastructure Improvements

Release Note Description

Install Python 3.6 on the SLES 12 image. This allowed us to increase the installed Python cryptography and
pyopenssl versions in our sles.12.* queues to to 41.0.1 and 23.2.0, respectively. Due to restrictions in our infrastructure, this change will be reflected on https://helix.dot.net as >=39.0.1 and >=23.0.0 rather than the exact versions installed.

See dotnet/arcade#13186 for a similar but much more broad change affecting the cryptography and pyopenssl versions installed in our images.

[dougbu]

!32479 fix has rolled out