Adapt to new libQuotient API changes

postPlainText is gone

src/models/actionsmodel.cpp

@@ -136,7 +136,11 @@ QList<ActionsModel::Action> actions{
     Action{
         u"plain"_s,
         [](const QString &text, NeoChatRoom *room, ChatBarCache *) {
+#if Quotient_VERSION_MINOR > 9
+            room->postText(text.toHtmlEscaped());
+#else
             room->postPlainText(text.toHtmlEscaped());
+#endif
             return QString();
         },
         std::nullopt,