Fix missed typings

[microbit-matt-hillsdon]

Work on the V3 editor docs make it pretty clear I missed some!

[microbit-matt-hillsdon]

Full list:

• [x] microphone.is_event(event: Unknown) -> Unknown
• [x] is_event(event: Unknown) -> Unknown
• [x] get_tempo(self: Unknown) -> Tuple[int, int]
• [x] pitch(frequency: int, duration: Unknown = ..., pin: MicroBitDigitalPin = ..., wait: bool = ...)
• [x] read_light_level() -> Unknown
• [x] write(addr: int, buf: bytes | bytearray, repeat: Unknown = False)

Would be good to reinstate actual values for details too where we can. I think I was too eager to elide and it does the docs no favours. Track separately.