Add VNImageRequestHandler::perform as safe function

Author: jgeralnik

Vision/VNRequestHandler.rs

@@ -64,7 +64,7 @@ extern_methods!(
 
         #[cfg(feature = "VNRequest")]
         #[method(performRequests:error:_)]
-        pub unsafe fn performRequests_error(
+        pub fn performRequests_error(
             &self,
             requests: &NSArray<VNRequest>,
         ) -> Result<(), Retained<NSError>>;