Fix build

tools/gradle-plugin/src/main/kotlin/BuildMiraiPluginTask.kt

@@ -11,6 +11,7 @@ package net.mamoe.mirai.console.gradle
 
 import com.github.jengelman.gradle.plugins.shadow.tasks.ShadowJar
 import org.gradle.api.tasks.CacheableTask
+import org.gradle.api.tasks.Internal
 import org.jetbrains.kotlin.gradle.plugin.KotlinTarget
 import java.io.File
 import javax.inject.Inject
@@ -22,6 +23,7 @@ public open class BuildMiraiPluginTask @Inject constructor(
     /**
      * ShadowJar 打包结果
      */
+    @get:Internal
     public val output: File
         get() = outputs.files.singleFile