fix: update clickedUrl parameter type to allow null values in trackInAppClose method per PR comment

Author: lposen

ios/RNIterableAPI/RNIterableAPI.mm

@@ -179,7 +179,7 @@ - (void)trackInAppClick:(NSString *)messageId
 - (void)trackInAppClose:(NSString *)messageId
                location:(double)location
                  source:(double)source
-             clickedUrl:(NSString *)clickedUrl {
+             clickedUrl:(NSString *_Nullable)clickedUrl {
   [_swiftAPI trackInAppClose:messageId
                     location:location
                       source:source

src/api/NativeRNIterableAPI.ts

@@ -54,7 +54,7 @@ export interface Spec extends TurboModule {
     messageId: string,
     location: number,
     source: number,
-    clickedUrl?: string
+    clickedUrl?: string | null
   ): void;
   inAppConsume(messageId: string, location: number, source: number): void;