fix: Byte mismatch issue

I hypothesize that this is due to a potential race condition between two
recorders when the keyboard has been destroyed while recording. When the
keyboard has been recreated, it will start a second new recorder. Since
the first recorder isn't stopped, sending a request based on the file
may lead to mismatch between file header size and actual file size,
since the file is being written to while being read.

Full error message:

```
expected X bytes but received Y
```

Note that Y will be larger than X.

Fixes: #40

android/app/src/main/java/com/example/whispertoinput/WhisperInputService.kt

@@ -211,4 +211,10 @@ class WhisperInputService : InputMethodService() {
         recorderManager!!.stop()
     }
 
+    override fun onDestroy() {
+        super.onDestroy()
+        whisperTranscriber.stop()
+        whisperKeyboard.reset()
+        recorderManager!!.stop()
+    }
 }