Add missing exceptions field to TracebackException (#13204)

Author: kevinji

stdlib/traceback.pyi

@@ -115,6 +115,8 @@ if sys.version_info >= (3, 11):
 class TracebackException:
     __cause__: TracebackException
     __context__: TracebackException
+    if sys.version_info >= (3, 11):
+        exceptions: list[TracebackException] | None
     __suppress_context__: bool
     stack: StackSummary
     filename: str