Automatic dependency update PRs should include version information

[lbussell]

We should consider adding the SDK build number to automatic dependency update PRs in this repo.

This would provide a few benefits:

• easier to evaluate the correctness of dependency flow PRs at a glance
• there won't be tons of commits in the history that all have the same commit message
• easier to trace back changes to specific .NET versions without diving into the diffs (for example, if an update needed to have a workaround added)

[lbussell]

[Triage] One downside to changing the title is that it breaks email grouping for team members who use email notifications. Putting the version in the body would fix this, but then we wouldn't get to see the build version in the commit history.

[lbussell]

[Triage] Another thing to consider is how the bot would need to update the title of the PR when it's force updated.

Seeing as this work would be non-trivial, it is probably not a good ROI at the moment.

[lbussell]

[Triage] Another option would be to

1. Change the default squash-merge commit message at a repo level to include the PR description in the commit message.
2. Update the dependency update PR logic to include the version info in the PR description.

This would allow us some more visibility into dependency update commits as well as not break email chains.