Support newVersion and prevVersion for updates with multiple dependencies

[Nishnha]

Add support for the newVersion and prevVersion fields for updates with multiple dependencies.

Right now these fields are empty when there are multiple dependencies, so this affects both grouped updates and transitive dependency updates.

[Nishnha]

I took an initial pass at resolving this for grouped updates with https://github.com/dependabot/fetch-metadata/compare/nishnha/grouped-updates-support...nishnha/support-version-info?expand=1

We can pull version info from the commit metadata, but we will need to make sure the commit message version string ends in a period for the regex we have in place to work.

Then we can check against the name of the dependency and hopefully return the correct newVersion and prevVersion

[inomdzhon]

I want this feature 😭😭😭