Fix/datetime warning (#202)

* Fix deprecation warning (utcnow)

* Mypy

src/neo4j_graphrag/experimental/pipeline/pipeline.py

@@ -15,12 +15,12 @@
 from __future__ import annotations
 
 import asyncio
+import datetime
 import enum
 import logging
 import uuid
 import warnings
 from collections import defaultdict
-from datetime import datetime
 from timeit import default_timer
 from typing import Any, AsyncGenerator, Optional
 
@@ -61,7 +61,9 @@ class RunStatus(enum.Enum):
 class RunResult(BaseModel):
     status: RunStatus = RunStatus.DONE
     result: Optional[DataModel] = None
-    timestamp: datetime = Field(default_factory=datetime.utcnow)
+    timestamp: datetime.datetime = Field(
+        default_factory=lambda: datetime.datetime.now(datetime.timezone.utc)
+    )
 
 
 class TaskPipelineNode(PipelineNode):

tests/unit/experimental/pipeline/test_pipeline.py

@@ -16,12 +16,14 @@
 
 import asyncio
 import tempfile
+from typing import Sized
 from unittest import mock
 from unittest.mock import AsyncMock, call, patch
 
 import pytest
 from neo4j_graphrag.experimental.pipeline import Component, Pipeline
 from neo4j_graphrag.experimental.pipeline.exceptions import PipelineDefinitionError
+from neo4j_graphrag.experimental.pipeline.pipeline import RunResult
 
 from .components import (
     ComponentAdd,
@@ -404,3 +406,8 @@ def test_pipeline_draw_missing_pygraphviz_dep() -> None:
     t = tempfile.NamedTemporaryFile()
     with pytest.raises(ImportError):
         pipe.draw(t.name)
+
+
+def test_run_result_no_warning(recwarn: Sized) -> None:
+    RunResult()
+    assert len(recwarn) == 0