clear all players when closing game tab

this prevents issues caused by items in play when using the player
destructor in the wrong order

cockatrice/src/interface/widgets/tabs/tab_game.cpp

@@ -259,6 +259,9 @@ TabGame::~TabGame()
     if (replayManager) {
         delete replayManager->replay;
     }
+    for (auto &player : game->getPlayerManager()->getPlayers()) {
+        player->clear();
+    }
 }
 
 void TabGame::updatePlayerListDockTitle()