你好我正在努力学习android开发，但是我总是遇到一个错误，我该怎么解决这个问题呢？

Caused by: org.gradle.internal.metaobject.AbstractDynamicObject$CustomMessageMissingMethodException: Could not find method clean() for arguments [{type=class org.gradle.api.tasks.Delete}, build_60vdswszrtm419of8bb1ep4tm$_run_closure1$_closure5@6472bcdb] on object of type org.gradle.api.internal.initialization.DefaultScriptHandler.

这是我的 build.gradle 文件：

buildscript {
    repositories { google()
        jcenter()
        mavenCentral()
        maven { url "https://jitpack.io" } }

    dependencies {
        classpath 'com.android.tools.build:gradle:4.1.3'
    }

    allprojects {
        repositories { google()
            jcenter()
            mavenCentral()
            maven { url "https://jitpack.io" } }
    }

    task clean(type: Delete) {
        delete rootProject.buildDir
    }
}