fix: 修复低功耗蓝牙写入特征值数据报错的Bug

src/platforms/app-plus/service/api/device/bluetooth.js

@@ -139,6 +139,8 @@ export function readBLECharacteristicValue (data, callbackId) {
 }
 
 export function writeBLECharacteristicValue (data, callbackId) {
+  if (typeof data.value === 'string') {
     data.value = base64ToArrayBuffer(data.value)
+  }
   bluetoothExec('writeBLECharacteristicValue', callbackId, data)
 }