fix videostream unpause

[MarcSkovMadsen]

Fixes https://discourse.holoviz.org/t/videostream-does-not-show-video-after-setting-paused-to-false/2525.

I.e. you can pause and the un-pause again.

videostream-works.mp4

import panel as pn
import time
pn.extension()
video = pn.widgets.VideoStream(timeout=100, paused=False)

pn.Column(video, video.param.paused).servable()

[codecov]

Codecov Report

Merging #2508 (ff4da35) into master (5d04322) will increase coverage by 0.00%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #2508   +/-   ##
=======================================
  Coverage   82.99%   82.99%           
=======================================
  Files         184      184           
  Lines       22723    22723           
=======================================
+ Hits        18859    18860    +1     
+ Misses       3864     3863    -1     

Impacted Files	Coverage Δ
panel/tests/pane/test_plotly.py	98.63% <0.00%> (+0.68%)	⬆️

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