[stdlib] Updates for Python 3.13.12 and 3.14.3 (#15371)

stdlib/email/headerregistry.pyi

@@ -1,3 +1,4 @@
+import sys
 import types
 from collections.abc import Iterable, Mapping
 from datetime import datetime as _datetime
@@ -137,6 +138,17 @@ class MessageIDHeader:
     @staticmethod
     def value_parser(value: str) -> MessageID: ...
 
+if sys.version_info >= (3, 13):
+    from email._header_value_parser import MessageIDList
+
+    # Added in Python 3.13.12, 3.14.3
+    class ReferencesHeader:
+        max_count: ClassVar[Literal[1]]
+        @classmethod
+        def parse(cls, value: str, kwds: dict[str, Any]) -> None: ...
+        @staticmethod
+        def value_parser(value: str) -> MessageIDList: ...
+
 @type_check_only
 class _HeaderParser(Protocol):
     max_count: ClassVar[Literal[1] | None]