Allow trusted Element Call to send encryption keys via to-device

src/stores/widgets/StopGapWidgetDriver.ts

@@ -200,6 +200,7 @@ export class StopGapWidgetDriver extends WidgetDriver {
                 EventType.CallSDPStreamMetadataChanged,
                 EventType.CallSDPStreamMetadataChangedPrefix,
                 EventType.CallReplaces,
+                EventType.CallEncryptionKeysPrefix,
             ];
             for (const eventType of sendRecvToDevice) {
                 this.allowedCapabilities.add(