Add ONNX export support for `PatchTST` #63

Job	Run time
build (3.10, macos-15, test_modeling_gemma2.py)	1h 2m 14s
build (3.10, macos-15, test_modeling_gemma.py)	56m 42s
build (3.10, macos-15, test_modeling_llama.py)	9m 14s
build (3.10, macos-15, test_modeling_olmo.py)	9m 5s
build (3.10, macos-15, test_modeling.py)	10m 12s
build (3.10, macos-15, test_modeling_qwen2.py)	4m 2s
build (3.11, macos-15, test_modeling_gemma2.py)	1h 0m 13s
build (3.11, macos-15, test_modeling_gemma.py)	42m 19s
build (3.11, macos-15, test_modeling_llama.py)	9m 49s
build (3.11, macos-15, test_modeling_olmo.py)	7m 57s
build (3.11, macos-15, test_modeling.py)	9m 27s
build (3.11, macos-15, test_modeling_qwen2.py)	3m 52s
build (3.12, macos-15, test_modeling_gemma2.py)	58m 24s
build (3.12, macos-15, test_modeling_gemma.py)	50m 40s
build (3.12, macos-15, test_modeling_llama.py)	14m 22s
build (3.12, macos-15, test_modeling_olmo.py)	11m 1s
build (3.12, macos-15, test_modeling.py)	9m 34s
build (3.12, macos-15, test_modeling_qwen2.py)	3m 36s
	7h 12m 43s

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