优化

app/src/main/java/io/legado/app/service/HttpReadAloudService.kt

@@ -33,7 +33,6 @@ import kotlinx.coroutines.ensureActive
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.sync.Mutex
 import kotlinx.coroutines.sync.withLock
-import kotlinx.coroutines.withContext
 import okhttp3.Response
 import org.mozilla.javascript.WrappedException
 import java.io.File