Fix build issue

Author: Jack251970

Plugins/Flow.Launcher.Plugin.Url/Main.cs

@@ -41,7 +41,7 @@ public class Main : IPlugin, IPluginI18n, ISettingProvider
             // resource path
             "(?:/\\S*)?" +
             "$";
-        Regex reg = new Regex(urlPattern, RegexOptions.Compiled | RegexOptions.IgnoreCase);
+        private readonly Regex UrlRegex = new(UrlPattern, RegexOptions.Compiled | RegexOptions.IgnoreCase);
         internal static PluginInitContext Context { get; private set; }
         internal static Settings Settings { get; private set; }