core: Put Python version as a project requirement so it is considered by ruff (#26608)

Ruff doesn't know about the python version in
`[tool.poetry.dependencies]`. It can get it from
`project.requires-python`.

Notes:
* poetry seems to have issues getting the python constraints from
`requires-python` and using `python` in per dependency constraints. So I
had to duplicate the info. I will open an issue on poetry.
* `inspect.isclass()` doesn't work correctly with `GenericAlias`
(`list[...]`, `dict[..., ...]`) on Python <3.11 so I added some `not
isinstance(type, GenericAlias)` checks:

Python 3.11
```pycon
>>> import inspect
>>> inspect.isclass(list)
True
>>> inspect.isclass(list[str])
False
```

Python 3.9
```pycon
>>> import inspect
>>> inspect.isclass(list)
True
>>> inspect.isclass(list[str])
True
```

Co-authored-by: Eugene Yurtsev <eyurtsev@gmail.com>

libs/core/tests/unit_tests/fake/callbacks.py

@@ -1,7 +1,7 @@
 """A fake callback handler for testing purposes."""
 
 from itertools import chain
-from typing import Any, Dict, List, Optional, Union
+from typing import Any, Optional, Union
 from uuid import UUID
 
 from pydantic import BaseModel
@@ -16,7 +16,7 @@ class BaseFakeCallbackHandler(BaseModel):
     starts: int = 0
     ends: int = 0
     errors: int = 0
-    errors_args: List[Any] = []
+    errors_args: list[Any] = []
     text: int = 0
     ignore_llm_: bool = False
     ignore_chain_: bool = False
@@ -265,8 +265,8 @@ class FakeCallbackHandler(BaseCallbackHandler, BaseFakeCallbackHandlerMixin):
 class FakeCallbackHandlerWithChatStart(FakeCallbackHandler):
     def on_chat_model_start(
         self,
-        serialized: Dict[str, Any],
-        messages: List[List[BaseMessage]],
+        serialized: dict[str, Any],
+        messages: list[list[BaseMessage]],
         *,
         run_id: UUID,
         parent_run_id: Optional[UUID] = None,

libs/core/tests/unit_tests/fake/test_fake_chat_model.py

@@ -1,7 +1,7 @@
 """Tests for verifying that testing utility code works as expected."""
 
 from itertools import cycle
-from typing import Any, Dict, List, Optional, Union
+from typing import Any, Optional, Union
 from uuid import UUID
 
 from langchain_core.callbacks.base import AsyncCallbackHandler
@@ -149,18 +149,18 @@ async def test_callback_handlers() -> None:
     """Verify that model is implemented correctly with handlers working."""
 
     class MyCustomAsyncHandler(AsyncCallbackHandler):
-        def __init__(self, store: List[str]) -> None:
+        def __init__(self, store: list[str]) -> None:
             self.store = store
 
         async def on_chat_model_start(
             self,
-            serialized: Dict[str, Any],
-            messages: List[List[BaseMessage]],
+            serialized: dict[str, Any],
+            messages: list[list[BaseMessage]],
             *,
             run_id: UUID,
             parent_run_id: Optional[UUID] = None,
-            tags: Optional[List[str]] = None,
-            metadata: Optional[Dict[str, Any]] = None,
+            tags: Optional[list[str]] = None,
+            metadata: Optional[dict[str, Any]] = None,
             **kwargs: Any,
         ) -> Any:
             # Do nothing
@@ -174,7 +174,7 @@ async def test_callback_handlers() -> None:
             chunk: Optional[Union[GenerationChunk, ChatGenerationChunk]] = None,
             run_id: UUID,
             parent_run_id: Optional[UUID] = None,
-            tags: Optional[List[str]] = None,
+            tags: Optional[list[str]] = None,
             **kwargs: Any,
         ) -> None:
             self.store.append(token)
@@ -185,7 +185,7 @@ async def test_callback_handlers() -> None:
         ]
     )
     model = GenericFakeChatModel(messages=infinite_cycle)
-    tokens: List[str] = []
+    tokens: list[str] = []
     # New model
     results = list(model.stream("meow", {"callbacks": [MyCustomAsyncHandler(tokens)]}))
     assert results == [