Handle topic updates

src/models/roommodel.cpp

@@ -65,6 +65,7 @@ void Room::applyEvents(const std::vector<mtx::events::collections::TimelineEvent
         else if (const auto ev = boost::get<StateEvent<state::PinnedEvents>>(&e.data)) {
         } else if (const auto ev = boost::get<StateEvent<state::PowerLevels>>(&e.data)) {
         } else if (const auto ev = boost::get<StateEvent<state::Topic>>(&e.data)) {
+            this->topic = ev->content.topic;
         } else if (const auto ev = boost::get<EncryptedEvent<msg::Encrypted>>(&e.data)) {
         } else if (const auto ev = boost::get<RedactionEvent<msg::Redaction>>(&e.data)) {
         } else if (const auto ev = boost::get<Sticker>(&e.data)) {