Fix Update Plenum Repo Dispatch script

[WadeBarnes]

The repoDispatchable_UpdatePlenumDependency.yaml script is called by the Plenum release process once a new version of Plenum is published. The script is meant to automate the process of summitting a PR to update indy-node with the latest version of plenum.

The PR creation step fails because the github.event.pusher.email field is blank at the time the script runs. The email address is expected to be the email of the github.actor. It might simply be the wrong field is being referenced to access the email address.

[WadeBarnes]

Manually submitted the PR this time around; #1831

[WadeBarnes]

The sed script setting the plenum version needs some tweaking to. It leaves out the closing '. For example: