fix CHANGES.md

Signed-off-by: Haochen M. Kotoi-Xie <hx@kxc.inc>

Author: haochenx

CHANGES.md

@@ -109,7 +109,6 @@ changelog properly.
 - Add `dune build --dump-gc-stats FILE` argument to dump garbage collection
   stats to a named file. (#8072, @Alizter)
 
-=======
 - Fix bug with ppx and Reason syntax due to missing dependency in sandboxed
   action (#7932, fixes #7930, @Alizter)