Add support for publishing verification results with a branch using the pact-ruby-standalone

[bethesque]

The Pact Broker now supports branches as first class entities. You can read more about this here: https://github.com/pact-foundation/docs.pact.io/blob/feat/deployments-and-releases/website/blog/2021-07-04-why-we-are-getting-rid-of-tags.md

To allow users to use this feature:

• Upgrade the pact-ruby-standalone to at least version 1.88.70
• Add an appropriately prefixed "branch" property to the user facing interface (make it match the existing provider name, tag, and version properties)
• Pass the branch through to the pact provider verifier CLI using the parameter --provider-version-branch

[mefellows]

Both v1.6.5 and the v2.0.0-beta.9 now support this, closing!

[bethesque]

🎉