Fixed custom module importing on Windows (#5891)
* Fixed custom module importing on Windows
Windows use back slash and `os.path.join()` follows that convention.
* Apply suggestions from code review
Co-authored-by: Lucain <lucainp@gmail.com>
* Update pipeline_utils.py
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Co-authored-by: Sayak Paul <spsayakpaul@gmail.com>
Co-authored-by: Lucain <lucainp@gmail.com>
