Fix "fatal: could not read Username..."

[TimHess]

The scheduled keep-alive job failed on it's first run with:

fatal: could not read Username for 'https://github.com/': No such device or address
Error: Process completed with exit code 128.

This happens when the job tries to run git push origin "$branch_name", effectively without credentials, because persist-credentials is set to false and we aren't completely configuring git another way.

We should be able to fix this by either:

• removing this:

  with:
    persist-credentials: false
  

• adding this:

  git remote set-url origin "https://x-access-token:${GH_TOKEN}@github.com/${GITHUB_REPOSITORY}.git"