add translation for download failed error msg

Author: jjw24

Plugins/Flow.Launcher.Plugin.PluginsManager/Languages/en.xaml

@@ -19,6 +19,8 @@
     <system:String x:Key="plugin_pluginsmanager_update_title">Plugin Update</system:String>
     <system:String x:Key="plugin_pluginsmanager_update_exists">This plugin has an update, would you like to see it?</system:String>
     <system:String x:Key="plugin_pluginsmanager_update_alreadyexists">This plugin is already installed</system:String>
+    <system:String x:Key="plugin_pluginsmanager_update_failed_title">Plugin Manifest Download Failed</system:String>
+    <system:String x:Key="plugin_pluginsmanager_update_failed_subtitle">Please check if you can connect to github.com. This error means you may not be able to install or update plugins.</system:String>
 
     <!--Controls-->
 

Plugins/Flow.Launcher.Plugin.PluginsManager/PluginsManager.cs

@@ -61,9 +61,8 @@ internal Task UpdateManifest()
             {
                 _downloadManifestTask = pluginsManifest.DownloadManifest();
                 _downloadManifestTask.ContinueWith(_ =>
-                        Context.API.ShowMsg("Plugin Manifest Download Fail.",
-                            "Please check if you can connect to github.com. " +
-                            "This error means you may not be able to Install and Update Plugin.", icoPath, false),
+                        Context.API.ShowMsg(Context.API.GetTranslation("plugin_pluginsmanager_update_failed_title"),
+                            Context.API.GetTranslation("plugin_pluginsmanager_update_failed_subtitle"), icoPath, false),
                     TaskContinuationOptions.OnlyOnFaulted);
                 return _downloadManifestTask;
             }