Add deprecation of HAVE_UMFPACK to changelog

This was an oversight in the MR !1294 (merged) that came up recently in #379 (closed): The preprocessor constant HAVE_UMFPACK is deprecated and will be removed until the next release 2.11. Use the macro HAVE_SUITESPARSE_UMFPACK instead. This change is already merged. This MR adds the corresponding changelog entry.

CHANGELOG.md

@@ -118,6 +118,8 @@ In order to build the DUNE core modules you need at least the following software
 
 - Deprecated `Hybrid::equals`. Use `Hybrid::equal_to` instead.
 
+- The preprocessor constant `HAVE_UMFPACK` is deprecated. Use `HAVE_SUITESPARSE_UMFPACK` instead.
+
 ## Python: Changelog
 
 - Python: Add `TupleVector` Python bindings