修复平台判断

FastGithub.Dns/DnsServerHostedService.cs

@@ -41,13 +41,15 @@ namespace FastGithub.Dns
             this.hostsValidator = hostsValidator;
             this.logger = logger;
 
+            options.OnChange(opt =>
+            {
                 if (OperatingSystem.IsWindows())
                 {
-                options.OnChange(opt => SystemDnsUtil.DnsFlushResolverCache());
+                    SystemDnsUtil.DnsFlushResolverCache();
                 }
+            });
         }
 
-
         /// <summary>
         /// 启动dns
         /// </summary>