Fix CUDARuntimeError import

tests/kernelcreation/test_reduction.py

@@ -2,7 +2,6 @@ import pytest
 import numpy as np
 
 import pystencils as ps
-from cupy_backends.cuda.api.runtime import CUDARuntimeError
 from pystencils.sympyextensions import reduction_assignment_from_str
 
 INIT_W = 5
@@ -51,6 +50,7 @@ def test_reduction_cpu(instruction_set, dtype, op):
 def test_reduction_gpu(dtype, op):
     try:
         import cupy as cp
+        from cupy_backends.cuda.api.runtime import CUDARuntimeError
 
         device_count = range(cp.cuda.runtime.getDeviceCount())
         print(f"Found {device_count} GPUs")