added ruff for code review

tests/test_optics_plot.py

@@ -2,7 +2,6 @@
 
 from __future__ import annotations
 
-import math
 import sys
 from pathlib import Path
 
@@ -11,14 +10,13 @@ import pytest
 np = pytest.importorskip("numpy")
 
 from orisys_sensor_design.optics import (
-    AIR_INDEX,
     Interface,
-    OpticsLayer,
     OpticalStack,
+    OpticsLayer,
     camera_rays,
+    quantify,
     sample_stack,
     summarize,
-    quantify,
 )
 from orisys_sensor_design.optics_plot import (
     DEFAULT_SANITY_MM,