Remove outdated comment

Author: encukou

Objects/unicodeobject.c

@@ -15632,18 +15632,7 @@ _PyUnicode_ClearInterned(PyInterpreterState *interp)
         int shared = 0;
         switch (PyUnicode_CHECK_INTERNED(s)) {
         case SSTATE_INTERNED_IMMORTAL:
-            /* Make immortal interned strings mortal again.
-             *
-             * Currently, the runtime is not able to guarantee that it can exit
-             * without allocations that carry over to a future initialization
-             * of Python within the same process. i.e:
-             *   ./python -X showrefcount -c 'import itertools'
-             *   [237 refs, 237 blocks]
-             *
-             * This should remain disabled (`Py_DEBUG` only) until there is a
-             * strict guarantee that no memory will be left after
-             * `Py_Finalize`.
-             */
+            /* Make immortal interned strings mortal again. */
             // Skip the Immortal Instance check and restore
             // the two references (key and value) ignored
             // by PyUnicode_InternInPlace().