Notify not received by client, a.k.a ESP32 can't send data to Android

ESP32 can't send data to Android, I fixed with a PR.
https://github.com/kakopappa/bluetooth_android_esp32_example/pull/3

In case that doesn't get merged soon an folks need to have this repo with ESP32 sending data to Android you can use our fork https://github.com/theselfdrivingboat-com/bluetooth_android_esp32_example
