Is correct this modification for work in a raspberry Pi?

Hi, I use my raspberry Pi B+ for sending data for serial UART port. TX pin

```python
uart = serial.Serial(port='/dev/ttyAMA0', baudrate=31250)

midi = adafruit_midi.MIDI(midi_out= uart, out_channel=0, debug=True)`
```

But this error appear:
```python
File "/home/raspbi/.local/lib/python3.9/site-packages/adafruit_midi/__init__.py", line 171, in _send
self._midi_out.write(packet, num)

TypeError: write() takes 2 positional arguments but 3 were given`

```

Work fine if delete 'num' argument..

Change this

```python
def _send(self, packet, num):
if self._debug:
print("Sending: ", [hex(i) for i in packet[:num]])
self._midi_out.write(packet, num)

```

To
```python
def _send(self, packet, num):
if self._debug:
print("Sending: ", [hex(i) for i in packet[:num]])
self._midi_out.write(packet)

```

It is correct?

Start with adafruit_midi/__init__.py, especially _send, and compare its _midi_out.write call with the serial.Serial API used by the Raspberry Pi snippet. Reproduce the TypeError with the shown UART configuration and determine which write signature preserves the intended packet handling; the issue is done when the example sends MIDI data without the argument-count error.

Written by the indexing model from the issue text.