Fixed iOS 15 NavigationBar color

Sources/iOS/Navigation/NavigationBar.swift

@@ -91,6 +91,14 @@ open class NavigationBar: UINavigationBar, Themeable {
       return barTintColor
     }
     set(value) {
+      if #available(iOS 15, *) {
+            let appearance = UINavigationBarAppearance()
+            appearance.configureWithOpaqueBackground()
+            appearance.backgroundColor = value
+            standardAppearance = appearance
+            scrollEdgeAppearance = standardAppearance
+        }
+        
       barTintColor = value
     }
   }