fix: exclude \Sabre\DAVACL\Plugin from prop find monitoring

Fixes creating events with attendees on the same server.

Signed-off-by: Richard Steinmetz <richard@steinmetz.cloud>

apps/dav/lib/Connector/Sabre/Server.php

@@ -86,6 +86,11 @@ class Server extends \Sabre\DAV\Server {
 			$parentFn($eventName, $callBack, $priority);
 			return;
 		}
+		// The \Sabre\DAVACL\Plugin needs to excluded as it relies on removeListener()
+		if ($pluginName === \Sabre\DAVACL\Plugin::class) {
+			$parentFn($eventName, $callBack, $priority);
+			return;
+		}
 
 		$callback = $this->getMonitoredCallback($callBack, $pluginName, $eventName);