youtube-dl: Update to 20210426

Changes:
20210426
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Extractors
+ [xfileshare] Add support for wolfstream.tv (#28858)
* [francetvinfo] Improve video id extraction (#28792)
* [medaltv] Fix extraction (#28807)
* [tver] Redirect all downloads to Brightcove (#28849)
* [go] Improve video id extraction (#25207, #25216, #26058)
* [youtube] Fix lazy extractors (#28780)
+ [bbc] Extract description and timestamp from __INITIAL_DATA__ (#28774)
* [cbsnews] Fix extraction for python <3.6 (#23359)

(leot)