Describe the bug

When I call the method NextRun() in a job I get a timestamp in the past. I think it's related to the fact that I am using a gocron.Locker and that particular instance does not get to do the job.
Then I can have the scenario that if for example, if my project have two instances, and I am exposing the nextRun value through an endpoint, the values are different for each instance.

I think I am not explaining myself very good, so that's why I created a repo to show it live, link below.

To Reproduce

I created a gist to describe the scenario:
https://gist.github.com/manuelarte/e33cec46cd8653a5e2731687041a051a

Version

github.com/go-co-op/gocron/v2 v2.15.0

Expected behavior

I would expect the NextRun value to be the same independently if that particular instance got the job last time or not.

Additional context

As mentioned before, I created a repo to easily show the issue https://github.com/manuelarte/cron-job-next-run-issue