Why I did it
This PR is part of sonic-mgmt-docker Python3 migration project.
Work item tracking
Microsoft ADO (number only): 24397943
How I did it
Upgrade Ansible to 6.7.0
Make Python3 as the default interpreter. python is a soft link to python3. If you want to use python2, use the command python2 explicitly.
Upgrade some pip packages to higher version in order to meet security requirement.
How to verify it
Build a private sonic-mgmt-docker successfully.
Verify python is python3.
Verify python2 is working with 202012 and 202205 branch.
Verify python3 is working with master branch.
Verify with github PR test.
