See #709 (comment)

Some pipelines get a 404 error when we try to make the automatic PR:

ERROR     Sync failed for nf-core/deepvariant:                       sync.py:385
GitHub API returned code 404:
{
    "message": "Not Found",
    "documentation_url": "https://developer.github.com/v3/pulls/#create-a-pull-request"
}

I don't know why this is happening, but we can try looping a few times with a sleep if we get specifically this error. Hopefully they will work on another go...?