Change from var to let for xdrip URL

FreeAPS/Sources/Modules/Home/HomeViewModel.swift

@@ -258,7 +258,7 @@ extension Home {
 
         func openCGM() {
             guard !settingsManager.settings.dontShowNS else {
-                var url = URL(string: "xdripswift://")!
+                let url = URL(string: "xdripswift://")!
                 UIApplication.shared.open(url, options: [:], completionHandler: nil)
                 return
             }