Summary with multi-languages is not supported in VEVENT block

Steps to reproduce

1. Import a VCALENDAR with multi-lang SUMMARY in VBLOCKS
2. Failure

Reproducer ICS: https://diplome.di.ens.fr/ical/INFO-M1-MODRES-S1.ics

Expected behavior

It should works as per https://icalendar.org/iCalendar-RFC-5545/3-2-10-language.html.

Actual behaviour

debug: b'<?xml version="1.0" encoding="utf-8"?>\n<d:error xmlns:d="DAV:" xmlns:s="http://sabredav.org/ns">\n  <s:exception>Sabre\\DAV\\Exception\\UnsupportedMediaType</s:exception>\n  <s:message>Validation error in iCalendar: SUMMARY MUST NOT appear more than once in a VEVENT component</s:message>\n</d:error>\n'

From the server.

Calendar app version

3.5.0

CalDAV-clients used

vdirsyncer

Browser

Not relevant

Client operating system

NixOS

Server operating system

NixOS

Web server

Nginx

Database engine version

PostgreSQL

PHP engine version

PHP 8.1

Nextcloud version

24.0.3

Updated from an older installed version or fresh install

Updated from an older version

List of activated apps

No response

Nextcloud configuration

No response

Web server error log

No response

Log file

No response

Browser log

No response

Additional info

No response

Start by importing the linked reproducer ICS with vdirsyncer and compare the multi-language SUMMARY fields with RFC 5545 section 3.2.10. Trace the validation that reports duplicate SUMMARY properties, then verify that the VEVENT is accepted without the UnsupportedMediaType error and that the language-specific summaries remain available.