Allow the OverlapDetector to be generic over input feature types

pybedlite/tests/test_overlap_detector.py

@@ -2,10 +2,10 @@
 
 from dataclasses import dataclass
 from typing import List
-from typing import TypeAlias
 from typing import Union
 
 import pytest
+from typing_extensions import TypeAlias
 
 from pybedlite.bed_record import BedRecord
 from pybedlite.bed_record import BedStrand