#231 Update release date

Author: astropenguin

CITATION.cff

@@ -4,7 +4,7 @@ message: "If you use this software, please cite it as below."
 title: "xarray-dataclasses"
 abstract: "xarray data creation by data classes"
 version: 1.9.0
-date-released: 2024-06-13
+date-released: 2024-12-09
 license: "MIT"
 doi: "10.5281/zenodo.4624819"
 url: "https://github.com/astropenguin/xarray-dataclasses"