btmanager script error 

The btmanager.sh script for rpi4_64 is encountering errors and spamming the following messages:

```
/root/btmanager.sh: line 49: rfcomm: command not found
/root/btmanager.sh: line 51: rfcomm: command not found
/root/btmanager.sh: line 49: rfcomm: command not found
/root/btmanager.sh: line 51: rfcomm: command not found
```

rfcomm also seems to be deprecated