Successfully compiled MinkowskiEngine under ubuntu20

[Jack-Dong-Dong]

Describe the bug
A clear and concise description of what the bug is.

A compilation success story

version0.5.4

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To Reproduce
Steps to reproduce the behavior. If the code is not attached and cannot be reproduced easily, the bug report will be closed without any comments.

• a minimally reproducible code.

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Expected behavior
A clear and concise description of what you expected to happen.

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Desktop (please complete the following information):

• OS: [e.g. Ubuntu 18.04]
• Python version: [e.g. 3.8.5]
• Pytorch version: [e.g. 1.9.1]
• CUDA version: [e.g. 11.1]
• Minkowski Engine version [e.g. 0.5.4]
• Output of the following command. (If you installed the latest MinkowskiEngine, paste the output of python -c "import MinkowskiEngine as ME; ME.print_diagnostics()". Otherwise, paste the output of the following command.)

wget -q https://raw.githubusercontent.com/NVIDIA/MinkowskiEngine/master/MinkowskiEngine/diagnostics.py ; python diagnostics.py

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Additional context
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