give contributors push access to xedni repo

[gammazero]

Summary

Give standard IPNI teams access to xedni repo. This gives contributors push access to the repo.

Why do you need this?

To be able to create PR's without requiring a fork of the repo.

What else do we need to know?

DRI: myself

Reviewer's Checklist

• It is clear where the request is coming from (if unsure, ask)
• All the automated checks passed
• The YAML changes reflect the summary of the request
• The Terraform plan posted as a comment reflects the summary of the request