Log Message:
youtube-dl: Update to 20200914

Changes:
20200914
--------
Core
+ [postprocessor/embedthumbnail] Add support for non jpg/png thumbnails
  (#25687, #25717)

Extractors
* [rtlnl] Extend URL regular expression (#26549, #25821)
* [youtube] Fix empty description extraction (#26575, #26006)
* [srgssr] Extend URL regular expression (#26555, #26556, #26578)
* [googledrive] Use redirect URLs for source format (#18877, #23919, #24689,
  #26565)
* [svtplay] Fix id extraction (#26576)
* [redbulltv] Improve support for rebull.com TV localized URLs (#22063)
+ [redbulltv] Add support for new redbull.com TV URLs (#22037, #22063)
* [soundcloud:pagedplaylist] Reduce pagination limit (#26557)