fix(macos): fix crash on calling custom protocol handler, closes #813 (…

…#814)

* fix(macos): fix crash on calling custom protocol handler

this bug was caused by change at #796 due to mismatch of function
signature

* Delete fix-wkwebview-crash.md

Co-authored-by: Amr Bashir <amr.bashir2015@gmail.com>

src/webview/wkwebview/mod.rs

@@ -113,7 +113,7 @@ impl InnerWebView {
         let function = this.get_ivar::<*mut c_void>("function");
         if !function.is_null() {
           let function = &mut *(*function
-            as *mut Box<dyn for<'s> Fn(&'s Request<Vec<u8>>) -> Result<Response<Vec<u8>>>>);
+            as *mut Box<dyn Fn(&Request<Vec<u8>>) -> Result<Response<Cow<'static, [u8]>>>>);
 
           // Get url request
           let request: id = msg_send![task, request];