Create CODEOWNERS

Author: diehlpk

.github/CODEOWNERS

@@ -0,0 +1,8 @@
+# Copyright (c) 2024 Patrick Diehl
+#
+# SPDX-License-Identifier: BSL-1.0
+# Distributed under the Boost Software License, Version 1.0. (See accompanying
+# file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+* @hkaiser
+* @diehlpk