Cannot create a holidays interval that ends today

[jaragunde]

This is a problem in holidayManagement.php. Steps to reproduce, assuming today is 2021-12-08:

1. Click on December 6.
2. Click on December 8.

Expected: A holiday interval is created between 6 and 8.
Actual: A single day is marked as holiday, the 8.

[jaragunde]

Additional facts:

• it doesn't happen if you try to create an interval starting on the 8th and ending later, e.g. 10.
• If you click first on Dec 8, then on Dec 6, no interval will be created.