nf-core sync: repeat attempt for failed pipelines

[ewels]

In the last sync, quite a lot of pipelines failed with a 404 error which essentially makes no sense.

As I don't know what causes this or how to fix it, a blunt approach could be to have a second loop after we finish which tries the syncing again with all failed pipelines. Hopefully that may then work on some of them and reduce the failure rate.

A more refined approach would be to detect 404 errors in the code, sleep for a few seconds and then try to open the PR again.

A combination of both of these could be good.

Phil

[ewels]

x-ref nf-core/mag#35 (comment)

[ewels]

Dup of #548