Issue #3411399: Adding '1 week' option to the 'Past horizon' field.

The proposed resolution is to extend the "Past horizon" field options by adding a '1 week' selection to that form. This addition will provide greater flexibility and usability for the module, catering to users who operate on a weekly event cycle. Navigate the Events Settings page on the module (/admin/config/google_calendar/events). Scroll down to Events Refresh section. Please note that 'Past horizon' field now includes '1 week' option.