Update `microphone.sound_level()` to use new CODAL features

[microbit-carlos]

A continuation from the discussion in:

• microphone.sound_level() values are too low #114

The CODAL updates have been pushed, but a new tag is not released yet (that'll take a few days more as other bug fixes are implemented):

• Sound level in MakeCode never reaches high values lancaster-university/codal-microbit-v2#225 (comment)

[microbit-carlos]

@dpgeorge CODAL v0.2.42 has been released:

• https://github.com/lancaster-university/codal-microbit-v2/releases/tag/v0.2.42
• lancaster-university/codal-microbit-v2@v0.2.41...v0.2.42

[dpgeorge]

New CODAL interface is used by c5ab627

[microbit-carlos]

As a heads up, I've raised this issue in the CODAL repo about this version of the audio.level:

• New audio.levelSPL returns fairly high values in a very quiet room. lancaster-university/codal-microbit-v2#236