Add Python Version to Auto's Canary Version Message on PRs

[KetanReddy]

Currently, when a canary is published, Auto will update the PR body with the version of the canary that was released. This version works for NPM/Maven/SPM/Cocopods packages as they all follow the same versioning but Python has unique requirements for what the version number can include. Our rules currently handle this for the actual publishing part but auto doesn't account for it so it requires a bit of digging to get the actual version number to use.