AutoLayoutModel returns None #223

Describe the bug

In Windows, AutoLayoutModel('lp://EfficientDete/PubLayNet') or AutoLayoutModel('lp://EfficientDet/PubLayNet') returns None. See reproducing steps.

To Reproduce
Steps to reproduce the behavior:

pip install layoutparser
pip install "layoutparser[layoutmodels]"
pip install "layoutparser[ocr]"
pip install asgiref 
pip install "layoutparser[detectron2]"                      

No error happens when installing these packages.

from layoutparser.models import AutoLayoutModel
model = AutoLayoutModel('lp://EfficientDete/PubLayNet')

Also tried:

from layoutparser.models import AutoLayoutModel
model = AutoLayoutModel('lp://EfficientDet/PubLayNet')  # maybe "Det" instead of "Dete", typo in documentation

Always there is model = None.

Environment

1. Please describe your Platform [Windows/MacOS/Linux]: Windows 10 64-bit
2. Please show the Layout Parser version 0.3.4
3. You may add addition that may be helpful for locating the problem, such as
   • How you installed PyTorch [e.g., pip, conda, source]
   • Other environment variables that may be related (such as $PATH, $LD_LIBRARY_PATH, $PYTHONPATH, etc.)

pytorch is installed as a dependency when installing layoutparser. I use pip package management.

CPU only.

Error traceback

No error returned.

Screenshots
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Additional context
Add any other context about the problem here.