Update version to 26.4.1 and changelog

Author: BradyPlanden

CHANGELOG.md

@@ -1,5 +1,11 @@
 # [Unreleased](https://github.com/pybamm-team/PyBaMM/)
 
+# [v26.4.1](https://github.com/pybamm-team/PyBaMM/tree/v26.4.1) - 2026-04-24
+
+## Bug fixes
+
+- Fixed overly-aggressive removal of solver step caches. ([#5458](https://github.com/pybamm-team/PyBaMM/pull/5458))
+
 # [v26.4.0](https://github.com/pybamm-team/PyBaMM/tree/v26.4.0) - 2026-04-22
 
 ## Features

CITATION.cff

@@ -24,6 +24,6 @@ keywords:
   - "expression tree"
   - "python"
   - "symbolic differentiation"
-version: "26.4.0"
+version: "26.4.1"
 repository-code: "https://github.com/pybamm-team/PyBaMM"
 title: "Python Battery Mathematical Modelling (PyBaMM)"