Fix close issue workflow

[carolynvs]

What does this change

I have forked the close issue workflow and edited it to support the new pull_request_target event type. I have submitted PRs upstream to the original workflow but until they are merged we can use this build of the github action.

What issue does it fix

The close issue workflow only supports pull_request, which does not have permission to close issues when the pull request was created from a fork.

Notes for the reviewer

N/A

Checklist

• Did you write tests?
• Did you write documentation?
• Did you change porter.yaml or a storage document record? Update the corresponding schema file.
• If this is your first pull request, please add your name to the bottom of our Contributors list. Thank you for making Porter better! 🙇‍♀️

Reviewer Checklist

• Comment with /azp run test-porter-release if a magefile or build script was modified
• Comment with /azp run porter-integration if it's a non-trivial PR