Update JOSS citation metadata to 3.4.4

Author: vahid-ahmadi

CITATION.cff

@@ -2,8 +2,8 @@ cff-version: 1.2.0
 message: "If you use this software, please cite it as below."
 type: software
 title: policyengine
-version: 3.4.0
-date-released: "2026-04-09"
+version: 3.4.4
+date-released: "2026-04-13"
 url: "https://github.com/PolicyEngine/policyengine.py"
 abstract: "An open-source Python package that provides a common analysis layer for tax-benefit microsimulation across the US and the UK."
 license: AGPL-3.0

paper.bib

@@ -55,7 +55,7 @@ @software{policyengine_core
 @software{policyengine_py,
   title={{policyengine}},
   author={{PolicyEngine Contributors}},
-  version={3.4.0},
+  version={3.4.4},
   url={https://github.com/PolicyEngine/policyengine.py},
   year={2026}
 }