Bugfix when end_frame is zero

[jihyeonyi]

Summary

Ticket Number: 144505
When video end_frame is zero, it was saved as None, not 0.
Due to this, end_frame information was lost when exporting it.

How to test

1. Make a video media with start_frame=0 and end_frame=0

   item = dm.DatasetItem(..., media=Video('video.mp4', start_frame=0, end_frame=0), ...)
   

2. export the dataset as datumaro format
3. check it the end_frame is described in the output json file
   ex.

   {
       "id": "video",
       ...,
       "video": {
           "path": "video.mp4",
           "step": 1,
           "start_frame": 0,
           "end_frame": 0
       }
   },
   

Checklist

• I have added unit tests to cover my changes.​
• I have added integration tests to cover my changes.​
• I have added the description of my changes into CHANGELOG.​
• I have updated the documentation accordingly

License

• I submit my code changes under the same MIT License that covers the project.
  Feel free to contact the maintainers if that's a concern.
• I have updated the license header for each file (see an example below).

# Copyright (C) 2024 Intel Corporation
#
# SPDX-License-Identifier: MIT

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.05%. Comparing base (63da2ff) to head (9b42bc4).
Report is 4 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #1541   +/-   ##
========================================
  Coverage    81.05%   81.05%           
========================================
  Files          276      276           
  Lines        32359    32359           
  Branches      6575     6575           
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  Hits         26230    26230           
  Misses        4684     4684           
  Partials      1445     1445           

Flag	Coverage Δ
ubuntu-20.04_Python-3.10	81.05% <100.00%> (ø)
windows-2022_Python-3.10	81.03% <100.00%> (ø)

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[sooahleex]

Looks good to me.