Daylight savings and leap years not accounted for in engagement delay

[brianhogg]

Reproduction Steps

1. Create an engagement with a multiple day delay
2. Fulfill that engagement (ie. completing a course) before a daylight savings change or leap year day, such that today + the delay will be after the time change or skipped day
3. Check when the engagement is scheduled under LifterLMS > Status > Scheduled Actions

Expected Behavior

The engagement happens when expected.

Actual Behavior

The engagement is an hour before or after the time expected (daylight savings change), or a day off (leap year)

This issue has be recreated:

• Locally
• On a staging site
• On a production website
• With only LifterLMS and a default theme