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: https://github.com/j3soon/whisper-to-input/issues/40