Update CUDA version in CI

Author: zfergus

.github/workflows/cuda.yml

@@ -40,7 +40,7 @@ jobs:
       - uses: Jimver/[email protected]
         id: cuda-toolkit
         with:
-          cuda: '12.3.2'
+          cuda: '12.6.1'
 
       - name: Get number of CPU cores
         uses: SimenB/[email protected]