[UX] tab3_coefficients.py: British spelling (optimization -> optimisation)

tabs/tab3_coefficients.py

@@ -515,6 +515,6 @@ def render_tab(cost_sliders):
     )
 
 
-    if st.button("Portfolio generation →", key="btn-nav-next-coefficients", type="primary", help="Run the optimization and generate your CDR portfolio."):
+    if st.button("Portfolio generation →", key="btn-nav-next-coefficients", type="primary", help="Run the optimisation and generate your CDR portfolio."):
         st.session_state["_navigate_to"] = "Portfolio generation"
         st.rerun()