New releases are no longer made to SourceForge and the GitHub releases
are considered official according to https://libjpeg-turbo.org, so
inherit github-releases and update the SRC_URI.
This now reports that we need to upgrade to 3.1.0.
Signed-off-by: Ross Burton <ross.burton@arm.com> Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>