move 'intel-extension-for-pytorch' to be optional

Signed-off-by: Cheng, Penghui <penghui.cheng@intel.com>

Author: PenghuiCheng

setup.py

@@ -42,7 +42,6 @@
         "onnx",
         "onnxruntime<1.15.0",
         "transformers>=4.33.0",
-        "intel-extension-for-pytorch",
     ],
     "openvino": ["openvino>=2023.1.0", "onnx", "onnxruntime", "transformers>=4.33.0"],
     "nncf": ["nncf>=2.6.0"],