test(feedback): use correct property in objc sample app

Author: armcknight

Samples/iOS-ObjectiveC/iOS-ObjectiveC/AppDelegate.m

@@ -122,6 +122,7 @@ - (BOOL)application:(UIApplication *)application
                     uiForm.useSentryUser = YES;
                 };
                 config.configureTheme = ^(SentryUserFeedbackThemeConfiguration *_Nonnull theme) {
+                    theme.fontFamily = @"ChalkboardSE-Regular";
                     theme.outlineStyle =
                         [[SentryFormElementOutlineStyle alloc] initWithColor:UIColor.purpleColor
                                                                 cornerRadius:10