Revert "gdb/python: Avoid use after free in py-tui.c"

This reverts commit 982a38f60b.

I missed that the title being assigned too was a std::string, and so
there is no leak.

gdb/python/py-tui.c

@@ -433,7 +433,7 @@ gdbpy_tui_set_title (PyObject *self, PyObject *newvalue, void *closure)
   if (value == nullptr)
     return -1;
 
-  win->window->title = value.release ();
+  win->window->title = value.get ();
   return 0;
 }