Update build.cs

enable source generator for build

Author: WeihanLi

build.cs

@@ -1,6 +1,6 @@
 foreach (var script in Directory.GetFiles(Directory.GetCurrentDirectory(), "*.cs", SearchOption.AllDirectories))
 {
     Console.WriteLine($"Compile script {script} test begin");
-    CommandExecutor.ExecuteCommandAndOutput($"dotnet-exec {script} --dry-run").EnsureSuccessExitCode();
+    CommandExecutor.ExecuteCommandAndOutput($"dotnet-exec {script} --generator --dry-run").EnsureSuccessExitCode();
     Console.WriteLine($"Compile script {script} test pass");
 }