Hotfix release 0.21.8

[Stypox]

Yet another hotfix release. No NewPipe-side PRs were included; instead all NewPipeExtractor PRs were included since cherry picking 55 commits possibly depending on the parent ones would not have been feasible. The PRs I had to include for this reason, but which were not essential for the hotfix, were anyway small PRs with no possible regression (TeamNewPipe/NewPipeExtractor#661 and TeamNewPipe/NewPipeExtractor#647). The detailed extractor changelog is here. Even though usually NewPipe's changelog do not contain NewPipeExtractor PRs references, I had to include them in this case because otherwise the changelog would have been empty. Anyway the changelog for NewPipe contains less dev-only details than that of NewPipeExtractor:

Fixed

• [YouTube] Fix buffering and throttling by decoding n parameter in stream URLs [YouTube] Fix buffering by decoding n parameter of stream urls NewPipeExtractor#683 Expand regex to match n param decrypt function NewPipeExtractor#696
• [YouTube] Fix comment extraction and more improvements [YouTube] Use the new internal API in NewPipe Extractor NewPipeExtractor#604
• [YouTube] Fix crashes with disabled comments Fix yt comments and add disabled comments functionallity NewPipeExtractor#652
• [YouTube] Fix music search Fix YouTube music search. NewPipeExtractor#699
• [PeerTube] Fix livestreams [PeerTube] Support livestreams NewPipeExtractor#661