handle occasional occurence of double run on daily job

[JohnRoesler]

What does this do?

we see an occasional instance of a daily job running twice within a second. this seems to be due to the job running too fast and starting a fraction of a second early such that it runs during the 1 second window before it should. this fix handles that case for daily jobs as those only run once at a given even hour/min/sec time.

Which issue(s) does this PR fix/relate to?

#52 (comment)

List any changes that modify/break current functionality

Have you included tests for your changes?

Did you document any new/modified functionality?

• Updated example_test.go
• Updated README.md

Notes