package/ply: bump version to 2.4.0
Bump to new available version.
For change log, see:
https://github.com/wkz/ply/releases/tag/2.4.0
Signed-off-by: Andreas Klinger <ak@it-klinger.de>
[Julien: replaced the change log url]
Signed-off-by: Julien Olivain <ju.o@free.fr>