Move changelog update to unreleased

CHANGELOG.md

@@ -1,10 +1,13 @@
 # [Unreleased](https://github.com/pybamm-team/PyBaMM/)
 
+## Features
+
+- Added a lithium ion equivalent circuit model with split open circuit voltages for each electrode. ([#4330](https://github.com/pybamm-team/PyBaMM/pull/4330))
+
 # [v24.9.0](https://github.com/pybamm-team/PyBaMM/tree/v24.9.0) - 2024-09-03
 
 ## Features
 
-- Added a lithium ion equivalent circuit model with split open circuit voltages for each electrode. ([#4330](https://github.com/pybamm-team/PyBaMM/pull/4330))
 - Added additional user-configurable options to the (`IDAKLUSolver`) and adjusted the default values to improve performance. ([#4282](https://github.com/pybamm-team/PyBaMM/pull/4282))
 - Added the diffusion element to be used in the Thevenin model. ([#4254](https://github.com/pybamm-team/PyBaMM/pull/4254))