[Bugfix] Weekly interval rules are sometimes calculated incorrectly

[jakebrady5]

The spec covers the context through which this bug was uncovered. Essentially generating occurrences_between for a relatively small date range was yielding false occurrences for weekly interval rules.

I observed that @time = @start_time if @time < @start_time was set to happen only when @start_time was falsey. Iterations past the first for a given rule in Schedule#next_time here in situations similar to the spec would pass in a time that was less than start_time.

Since @start_time was already defined in the rule, this @time value would be passed long for validation.

Most rules will then return immediately in this case, not applying their validation.

Any feedback is welcome!

[jakebrady5]

❤️ thank you @pacso

[pacso]

This looks correct @seejohnrun

[seejohnrun]

Thank you!

[pacso]

Of course, with the new checks this build now fails with a missing update to the changelog.

Could you do the honours @jakebrady5?