docs: add changelog

Author: kenjis

user_guide_src/source/changelogs/v4.5.0.rst

@@ -317,6 +317,7 @@ Changes
       :ref:`multiple-filters` are always enabled.
 - **RouteCollection:** The HTTP method keys in the protected property ``$routes``
   has been fixed from lowercase to uppercase.
+- ``declare(strict_types=1)`` has been added to most framework codebase.
 
 Deprecations
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