suggestion: Reduce log level of "Failed to schedule job" messages

[curita]

Background

Sometimes shub-workflow fails to schedule a job and retries the action until it succeeds or runs out of attempts.

In those situations, those "Failed to schedule job" messages will be reported as Errors, even though they don't require user actions other than waiting for those retries to finish.

Proposal

It would be nice for these messages to be considered warnings:

shub-workflow/shub_workflow/script.py

Line 388 in 50c85fe

logger.error(f"Failed to schedule job with arguments {schedule_kwargs}: {e}")

So they aren't flagged by monitors supervising log messages. If all retries made by @dash_retry_decorator fail, then the original issue is reraised, which seems to be reported as an error already.