Add cpu only version

[XuehaoSun]

Build from Source

pip install -r requirements.txt

# GPU
pip install -vvv --no-build-isolation -e .
# CPU
pip install -vvv --no-build-isolation -e .[cpu]
# HPU
pip install -vvv --no-build-isolation -e .[hpu]

Install from pypi

# GPU
pip install auto-round
# CPU
pip install auto-round[cpu]
# HPU
pip install auto-round[hpu]