Changelog: change  "version <next>" to "version 2.3"

Found-by: jamrial
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit faafd1e4f1fcc2d618633eae4dc532050b2be988)

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>