docs: add Deprecations

Author: kenjis

user_guide_src/source/changelogs/v4.3.0.rst

@@ -249,6 +249,7 @@ Deprecations
 - ``CodeIgniter::$path`` and ``CodeIgniter::setPath()`` are deprecated. No longer used.
 - The public property ``IncomingRequest::$uri`` is deprecated. It will be protected. Use ``IncomingRequest::getUri()`` instead.
 - The public property ``IncomingRequest::$config`` is deprecated. It will be protected.
+- Many methods and properties in ``CodeIgniter\Debug\Exceptions`` are deprecated. Because these methods have been moved to ``BaseExceptionHandler`` or ``ExceptionHandler``.
 
 Bugs Fixed
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