ci/test-matrix.yml: temporarily comment out gh200 nightly row

The gh200 runner currently hangs on stream-ordered memory allocator
calls (cudaMallocAsync). Disabling until the runner-side issue is
resolved.

Author: leofang

ci/test-matrix.yml

@@ -97,7 +97,9 @@ linux:
     - { ARCH: 'arm64', PY_VER: '3.12',  CUDA_VER: '12.9.1', LOCAL_CTK: '0', GPU: 'l4',         GPU_COUNT: '1', DRIVER: 'latest',     ENV: { MODE: 'nightly-numba-cuda' } }
     - { ARCH: 'arm64', PY_VER: '3.12',  CUDA_VER: '13.3.0', LOCAL_CTK: '0', GPU: 'l4',         GPU_COUNT: '1', DRIVER: 'latest',     ENV: { MODE: 'nightly-numba-cuda' } }
     # nightly-standard (arm64 nightly-only runners — per runner team request)
-    - { ARCH: 'arm64', PY_VER: '3.14',  CUDA_VER: '13.3.0', LOCAL_CTK: '1', GPU: 'gh200',      GPU_COUNT: '1', DRIVER: 'latest',     ENV: { MODE: 'nightly-standard' } }
+    # TODO: gh200 row disabled — currently hangs on stream-ordered memory
+    #       allocator (cudaMallocAsync); runner pool needs fixing first.
+    # - { ARCH: 'arm64', PY_VER: '3.14',  CUDA_VER: '13.3.0', LOCAL_CTK: '1', GPU: 'gh200',      GPU_COUNT: '1', DRIVER: 'latest',     ENV: { MODE: 'nightly-standard' } }
     - { ARCH: 'arm64', PY_VER: '3.14',  CUDA_VER: '13.3.0', LOCAL_CTK: '1', GPU: 'l4',         GPU_COUNT: '2', DRIVER: 'latest',     ENV: { MODE: 'nightly-standard' } }
     - { ARCH: 'arm64', PY_VER: '3.14t', CUDA_VER: '13.3.0', LOCAL_CTK: '1', GPU: 'l4',         GPU_COUNT: '2', DRIVER: 'latest',     ENV: { MODE: 'nightly-standard' } }