Explicitly specify embeddable=true when updating youtube video visibility

[mbertrand]

Pre-Flight checklist

• Testing
  • Code is tested
  • Changes have been manually tested

What are the relevant tickets?

Closes #1021

What's this PR do?

Specifies embeddable=True when updating youtube metadata status so that it won't be reverted.

How should this be manually tested?

• Copy YT_* values from RC to your .env file
• For one of your sites (with starter=ocw-course), add a small video to the site's Google Drive folder and sync.
• Once you have a video resource, update its title and description.
• Change the Youtube ID field to ulPWKn5hJ3w and save.
• In a shell, create a VideoFile object associated with this youtube id and then update metadata with version "live":

  video = VideoFile.objects.create(video=Video.objects.create(website=<your_website>), destination_id="ulPWKn5hJ3w")
  update_youtube_metadata(website, version="live")
  

• Check that the youtube video is still embeddable with public visibility (I can check for you on the test channel)

[codecov-commenter]

Codecov Report

Merging #1022 (d0e00d5) into master (cc50b15) will increase coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1022      +/-   ##
==========================================
+ Coverage   90.56%   90.57%   +0.01%     
==========================================
  Files         196      196              
  Lines        7547     7547              
  Branches     1318     1318              
==========================================
+ Hits         6835     6836       +1     
  Misses        627      627              
+ Partials       85       84       -1     

Impacted Files	Coverage Δ
videos/youtube.py	97.60% <ø> (ø)
static/js/util/factories/websites.ts	98.50% <0.00%> (+1.49%)	⬆️

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[alicewriteswrongs]

looks good!