anthropic[major]: support python 3.13 (#27916)

Last week Anthropic released version 0.39.0 of its python sdk, which
enabled support for Python 3.13. This release deleted a legacy
`client.count_tokens` method, which we currently access during init of
the `Anthropic` LLM. Anthropic has replaced this functionality with the
[client.beta.messages.count_tokens()
API](https://github.com/anthropics/anthropic-sdk-python/pull/726).

To enable support for `anthropic >= 0.39.0` and Python 3.13, here we
drop support for the legacy token counting method, and add support for
the new method via `ChatAnthropic.get_num_tokens_from_messages`.

To fully support the token counting API, we update the signature of
`get_num_tokens_from_message` to accept tools everywhere.

---------

Co-authored-by: Bagatur <22008038+baskaryan@users.noreply.github.com>

libs/core/tests/unit_tests/messages/test_utils.py

@@ -1,5 +1,8 @@
 import base64
 import json
+import typing
+from collections.abc import Sequence
+from typing import Any, Callable, Optional, Union
 
 import pytest
 
@@ -19,6 +22,7 @@ from langchain_core.messages.utils import (
     merge_message_runs,
     trim_messages,
 )
+from langchain_core.tools import BaseTool
 
 
 @pytest.mark.parametrize("msg_cls", [HumanMessage, AIMessage, SystemMessage])
@@ -431,7 +435,15 @@ def dummy_token_counter(messages: list[BaseMessage]) -> int:
 
 
 class FakeTokenCountingModel(FakeChatModel):
-    def get_num_tokens_from_messages(self, messages: list[BaseMessage]) -> int:
+    def get_num_tokens_from_messages(
+        self,
+        messages: list[BaseMessage],
+        tools: Optional[
+            Sequence[
+                Union[typing.Dict[str, Any], type, Callable, BaseTool]  # noqa: UP006
+            ]
+        ] = None,
+    ) -> int:
         return dummy_token_counter(messages)