http请求在AndroidStudio中的Kotlin上不起作用

implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.5.0'
implementation 'com.squareup.okhttp3:okhttp:4.9.1'

import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.withContext
import okhttp3.OkHttpClient
import okhttp3.Request
import okhttp3.Response

suspend fun makeHttpRequest(url: String): String {
    return withContext(Dispatchers.IO) {
        val client = OkHttpClient()
        val request = Request.Builder()
            .url(url)
            .build()
        val response: Response = client.newCall(request).execute()
        return@withContext response.body()?.string() ?: ""
    }
}

import androidx.lifecycle.ViewModel
import kotlinx.coroutines.*

class MyViewModel : ViewModel() {
    private val viewModelScope = CoroutineScope(Dispatchers.Main + SupervisorJob())

    fun fetchData() {
        viewModelScope.launch {
            val response = makeHttpRequest("https://example.com/api/data")
            // 处理返回的数据
        }
    }

    override fun onCleared() {
        super.onCleared()
        viewModelScope.cancel()
    }
}