fix icon

tools/termination/approve.md

@@ -5,7 +5,7 @@ title = 'AProVE TODO'
 subtitle = 'Probabilistic Model Checker'
 links = [
     { title = "Homepage", url = "https://cvc5.github.io/", icon = 'fa-solid fa-home' },
-    { title = "Source Code", url = "https://github.com/dreal/dreal4", icon = 'fa-brands fa-github'  },
+    { title = "Source Code", url = "https://github.com/dreal/dreal4", icon = 'fa-solid fa-code'  },
     { title = "Playground", url = "https://cvc5.github.io/app/", icon = 'fa-solid fa-gamepad' }
 ]
 applications = ['Probabilistic Model Checker', 'Rare Events']