BF: Only write ROI stop code if has a stop value

[TEParsons]

Cherry picked from dev

[codecov]

Codecov Report

Merging #5156 (a2738c6) into release (3459b45) will decrease coverage by 0.60%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           release    #5156      +/-   ##
===========================================
- Coverage    45.78%   45.18%   -0.61%     
===========================================
  Files          307      307              
  Lines        61669    61670       +1     
  Branches     10760    10761       +1     
===========================================
- Hits         28234    27864     -370     
- Misses       30974    31366     +392     
+ Partials      2461     2440      -21     

Impacted Files	Coverage Δ
psychopy/experiment/components/roi/__init__.py	79.45% <100.00%> (+0.14%)	⬆️
psychopy/platform_specific/darwin.py	0.00% <0.00%> (-48.64%)	⬇️
psychopy/gui/qtgui.py	12.17% <0.00%> (-26.93%)	⬇️
psychopy/microphone.py	13.27% <0.00%> (-20.18%)	⬇️
psychopy/platform_specific/__init__.py	47.05% <0.00%> (-11.77%)	⬇️
psychopy/constants.py	58.06% <0.00%> (-6.46%)	⬇️
psychopy/web.py	37.24% <0.00%> (-4.14%)	⬇️
psychopy/visual/backends/pygletbackend.py	42.04% <0.00%> (-4.05%)	⬇️
psychopy/hardware/__init__.py	75.71% <0.00%> (-2.86%)	⬇️
psychopy/info.py	50.00% <0.00%> (-2.62%)	⬇️
... and 11 more

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