Changelog: release is 2.5 not "next"

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
diff --git a/Changelog b/Changelog
index 98bd2c6..0130ca8 100644
--- a/Changelog
+++ b/Changelog
@@ -1,7 +1,7 @@
 Entries are sorted chronologically from oldest to youngest within each release,
 releases are sorted from youngest to oldest.
 
-version <next>:
+version 2.5:
 - HEVC/H.265 RTP payload format (draft v6) packetizer
 - SUP/PGS subtitle demuxer
 - ffprobe -show_pixel_formats option