Title: #3493: [Backport][ipa-4-8] azure-pipelines.yml: switch to Python 3.7
This PR was opened automatically because PR #3492 was pushed to master and backport to
ipa-4-8 is required.
To pull the PR as Git branch:
git remote add ghfreeipa https://github.com/freeipa/freeipa
git fetch ghfreeipa pull/3493/head:pr3493
git checkout pr3493