[3.13] gh-120289: Add external timer in traverse of _lsprof.Profiler (GH-121998) (#122000)

gh-120289: Add external timer in traverse of _lsprof.Profiler (GH-121998)
(cherry picked from commit eaf094c)

Co-authored-by: Tian Gao <[email protected]>

Author: miss-islington

Modules/_lsprof.c

@@ -856,6 +856,7 @@ static int
 profiler_traverse(ProfilerObject *op, visitproc visit, void *arg)
 {
     Py_VISIT(Py_TYPE(op));
+    Py_VISIT(op->externalTimer);
     return 0;
 }