Bump sabre dav to 4.7.1

[CarlSchwan]

Summary

See nextcloud/3rdparty#2526

TODO

• ...

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)
• Labels added where applicable (ex: bug/enhancement, 3. to review, feature component)
• Milestone added for target branch/version (ex: 32.x for stable32)

AI (if applicable)

• The content of this PR was partly or fully generated using AI

[Copilot]

Pull request overview

Updates Nextcloud’s DAV integration and test fixtures to align with the newer Sabre DAV/VObject behavior expected after the dependency bump referenced in nextcloud/3rdparty.

Changes:

• Update multiple ICS/VCF fixtures and calendar test XML payloads to the new Sabre VObject PRODID version string.
• Adjust Sabre connector method signatures (ObjectTree::copy, Directory::copyInto) to match the updated Sabre DAV APIs that include a depth argument.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tests/lib/Calendar/ManagerTest.php	Updates expected VCALENDAR PRODID in free/busy responses.
tests/data/ics/free-busy-request.ics	Updates fixture PRODID string.
tests/data/ics/event-builder-without-attendees.ics	Updates fixture PRODID string.
tests/data/ics/event-builder-complete.ics	Updates fixture PRODID string.
apps/dav/tests/unit/test_fixtures/example-event-default-expected.ics	Updates fixture PRODID string used by DAV unit tests.
apps/dav/lib/ExampleContentFiles/exampleContact.vcf	Updates example VCF PRODID string.
apps/dav/lib/Connector/Sabre/ObjectTree.php	Updates copy() signature to accept depth (but currently does not use it).
apps/dav/lib/Connector/Sabre/Directory.php	Updates copyInto() signature to accept depth (but currently does not use it).

Comments suppressed due to low confidence (1)

apps/dav/lib/Connector/Sabre/ObjectTree.php:162

• The new $depth argument is currently ignored. For WebDAV COPY on collections, Depth: 0 vs infinity changes semantics; always performing a recursive copy can violate the request and Sabre\DAV's expectations after the signature change.

	public function copy($sourcePath, $destinationPath, int $depth = Server::DEPTH_INFINITY): void {
		if (!$this->fileView) {
			throw new \Sabre\DAV\Exception\ServiceUnavailable('filesystem not setup');
		}

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[kesselb]

Should we update the existing beforeCopy / afterCopy listeners for the new depth argument?