MNT #321 remove comments

Author: prjemian

hkl/configuration.py

@@ -245,8 +245,7 @@ class DCSample:
     (the reciprocal of the crystal) in an orthonormal system.
     """
 
-    # TODO: Once py38 is dropped, re-enable the default value setting
-    U: List[List[float]]  # = field(default_factory=list[list[float]])
+    U: List[List[float]]
     """
     Orientation matrix (3 x 3) of the crystal relative to the diffractometer.
     (optional)