[BUGFIX] Get correct year for weekConfig. Use ISO 8601 week-numbering year

[cdaecke]

When browsing the calendar by week, I get the wrong year after calendar week 52. It gives me the year 2024 instead of 2025.

sf_event_mgt/Resources/Private/Templates/Event/Calendar.html

Lines 11 to 34 in 5fa7286

	<f:comment>
	=== Browse calendar by week ====
	<ul class="event-calendar__browser">
	<li class="event-calendar__browser-prev">
	<f:link.action rel="nofollow" action="calendar" controller="Event" arguments="{overwriteDemand:{week: weekConfig.previous.weeknumber, year: weekConfig.previous.year}}">
	&larr; <f:translate key="calendar.week" /> {weekConfig.previous.weeknumber}
	</f:link.action>
	</li>
	<li class="event-calendar__browser-current"><h3><f:translate key="calendar.week" /> {weekConfig.current.weeknumber}</h3></li>
	<li class="event-calendar__browser-next">
	<f:link.action rel="nofollow" action="calendar" controller="Event" arguments="{overwriteDemand:{week: weekConfig.next.weeknumber, year: weekConfig.next.year}}">
	<f:translate key="calendar.week" /> {weekConfig.next.weeknumber} &rarr;
	</f:link.action>
	</li>
	</ul>
	<ul class="event-calendar__days">
	<f:for each="{weeks.{weekConfig.current.weeknumber}}" as="day">
	<f:render partial="Event/CalendarDayItem" arguments="{day: day, settings: settings}"/>
	</f:for>
	</ul>
	</f:comment>

Debugging $firstDayNextWeek gives me 2024-12-30 which results in "2024" for the parameter tx_sfeventmgt_pieventcalendar[overwriteDemand][year]=2024 but it should be 2025.

sf_event_mgt/Classes/Service/CalendarService.php

Line 163 in 5fa7286

$firstDayNextWeek = (clone $firstDayOfCurrentWeek)->modify('+1 week');

This pull request addresses this issue, by using the parameter o for formatting the year.

The PHP manual states for the parameter the following:
ISO 8601 week-numbering year. This has the same value as Y, except that if the ISO week number (W) belongs to the previous or next year, that year is used instead.

[derhansen]

Thanks for finding the issue and for providing a PR to fix it. I will now merge the patch and extend unit tests afterwards, so the issue is covered by tests.