Use Optional for type hints to ensure backward compatibility.

Replaced PEP 604 union syntax (|) with Optional for type hints to maintain compatibility with Python versions earlier than 3.10.

src/pytest_replay/__init__.py

@@ -6,6 +6,7 @@
 from dataclasses import asdict
 from glob import glob
 from typing import Any
+from typing import Optional
 
 import pytest
 
@@ -47,8 +48,8 @@ def pytest_addoption(parser):
 class ReplayTestMetadata:
     nodeid: str
     start: float = 0.0
-    finish: float | None = None
-    outcome: str | None = None
+    finish: Optional[float] = None
+    outcome: Optional[str] = None
     metadata: dict[str, Any] = dataclasses.field(default_factory=dict)
 
     def to_clean_dict(self) -> dict[str, Any]: