Remove 12.9 CUDA test jobs (#867)

Author: NicolasHug

.github/workflows/linux_cuda_wheel.yaml

@@ -67,9 +67,10 @@ jobs:
           # For the actual release we should add that label and change this to
           # include more python versions.
         python-version: ['3.10']
-        # We test against 12.6 and 12.9 to avoid having too big of a CI matrix,
+        # We test against 12.6 to avoid having too big of a CI matrix,
         # but for releases we should add 12.8.
-        cuda-version: ['12.6', '12.9']
+        # TODO add 13.0!
+        cuda-version: ['12.6']
         # TODO: put back ffmpeg 5 https://github.com/pytorch/torchcodec/issues/325
         ffmpeg-version-for-tests: ['4.4.2', '6', '7']