Pin AMD to 6.4.4 (#881)

Author: oulgen

.github/matrix.json

@@ -66,8 +66,8 @@
       "runner": "linux.rocm.gpu.gfx942.2",
       "python-version": "3.12",
       "ref-eager": false,
-      "image": "rocm/dev-ubuntu-24.04:7.0-complete",
-      "runtime-version": "rocm7.0",
+      "image": "rocm/dev-ubuntu-24.04:6.4.4-complete",
+      "runtime-version": "rocm6.4",
       "container-options": "--device=/dev/kfd --device=/dev/dri",
       "pytorch-version": "pytorch-nightly",
       "alias": "mi325x"