Replace a link that's now broken.

The original download link on blender.org still works
(https://download.blender.org/peach/bigbuckbunny_movies/big_buck_bunny_1080p_surround.avi

)
but is still extremely slow.
Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>
(cherry picked from commit 223243d6

)
Signed-off-by: Armin Kuster <akuster808@gmail.com>