add date to citation

Baxter Eaves · Baxter Eaves · commit 2a4ef0e41cb7 · 2025-02-28T08:53:17.000-06:00
diff --git a/CITATION.cff b/CITATION.cff
@@ -30,3 +30,4 @@ keywords:
   - Mathematics
 license: MIT
 version: 0.18.1
+date-released: 2025-02-28
