Update changelog

Author: rmk135

docs/main/changelog.rst

@@ -7,6 +7,10 @@ that were made in every particular version.
 From version 0.7.6 *Dependency Injector* framework strictly 
 follows `Semantic versioning`_
 
+Development version
+-------------------
+- Regenerate C sources using Cython 0.26.
+
 3.6.0
 -----
 - Add ``CallableDelegate`` provider.