Failed to save and load checkpoints in UNet segmentation example

[xrhd]

I tried running the UNet_segmentation_example.ipynb demo on Google Colab, but I encountered the following error in several sections of the code, both when saving and loading checkpoints.

[xrhd]

I solved the problem using the resolve() method of pathlib.Path. I took the liberty of opening a small PR addressing the problem.

Note: I hope I have followed the contribution guide correctly.