Fix ExecuteCallbackWithCtx to use the context that was provided

This updates `ExecuteCallbackWithCtx` to use the context that was
provided.

lib/sdk.go

@@ -240,7 +240,7 @@ func (e *NucleiEngine) ExecuteCallbackWithCtx(ctx context.Context, callback ...f
 	}
 	e.resultCallbacks = append(e.resultCallbacks, filtered...)
 
-	_ = e.engine.ExecuteScanWithOpts(context.Background(), e.store.Templates(), e.inputProvider, false)
+	_ = e.engine.ExecuteScanWithOpts(ctx, e.store.Templates(), e.inputProvider, false)
 	defer e.engine.WorkPool().Wait()
 	return nil
 }