Set release date

Author: bernhardmgruber

CITATION.cff

@@ -21,7 +21,7 @@ authors:
   affiliation: "Helmholtz-Zentrum Dresden-Rossendorf, TU Dresden"
   orcid: "https://orcid.org/0000-0002-6702-2015"
 version: '0.6'
-date-released: '2023-01-31'
+date-released: '2024-02-29'
 repository-code: 'https://github.com/alpaka-group/llama'
 abstract: >-
   LLAMA is a cross-platform C++17/C++20 header-only template