link_card header fixed

bots/messaging_extension_action_preview_bot.py

@@ -393,7 +393,8 @@ class TeamsMessagingExtensionsActionPreviewBot(TeamsActivityHandler):
             url = f"https://{AppConfig.MARS_FQDN}/service-auth"
             card = CardHelper.load_assets_card("link_card",
                                                context=dict(title=title,
-                                                            url=url))
+                                                            url=url,
+                                                            header=header))
             attachments = [CardFactory.adaptive_card(card)]
             await turn_context.send_activity(
                 Activity(type=ActivityTypes.message, attachments=attachments)