obs-api: embed sanitize-4.0.0 to fix runtime issue

  When adding comments and other cases, obs-api calls unexistent
  function in sanitize 2.1.0, causing error 500 in webui.

Signed-off-by: Héctor Orón Martínez <hector.oron@collabora.co.uk>
Signed-off-by: Héctor Orón Martínez <zumbi@debian.org>