[torchlib] Fix layer norm dtype #8853

Job	Run time
build_docs (ubuntu-latest)	2m 39s
update_readme	5s
build_docs (windows-latest)	4m 14s
test (ubuntu-latest, py312)	18m 5s
test (ubuntu-latest, py311)	16m 34s
test (ubuntu-latest, py311-torch-nightly)	14m 52s
test (ubuntu-latest, py311-onnx-weekly)	15m 23s
test (ubuntu-latest, py311-ort-nightly)	3m 54s
test (ubuntu-latest, py310)	2m 57s
test (windows-latest, py312)	4m 21s
test (windows-latest, py311)	3m 44s
test (windows-latest, py311-torch-nightly)	3m 41s
test (windows-latest, py311-onnx-weekly)	4m 9s
test (windows-latest, py311-ort-nightly)	3m 55s
test (windows-latest, py310)	3m 56s
test (macos-latest, py312)	8m 7s
test (macos-latest, py311)	10m 29s
test (macos-latest, py311-torch-nightly)	7m 11s
test (macos-latest, py311-onnx-weekly)	8m 23s
test (macos-latest, py311-ort-nightly)	5m 51s
test (macos-latest, py310)	14m 20s
	2h 36m 50s

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