CHANGELOG: prepre tamplate for release

CHANGELOG.md

-v0.23 + 1
+v0.24 + 1
+-------
+
+### Changes or improvements
+
+### API additions
+
+### API removals
+
+### Breaking API changes
+
+v0.24
 -------
 
 ### Changes or improvements
@@ -65,6 +76,8 @@ v0.23 + 1
 
 ### API removals
 
+* No APIs were removed in this version.
+
 ### Breaking API changes
 
 * The `git_merge_tree_flag_t` is now `git_merge_flag_t`.  Subsequently,