headphoneAudioExposure uses incorrect unit pascal, should be decibelAWeightedSoundPressureLevel

[zrj1884]

Description:
When attempting to read data from HKQuantityTypeIdentifierHeadphoneAudioExposure, the app crashes with the following error:
Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Attempt to convert incompatible units: dBASPL, Pa'

Cause:
The code currently uses .pascal() as the unit for reading headphoneAudioExposure, which is not compatible with this quantity type.

According to Apple’s HealthKit documentation, HKQuantityTypeIdentifierHeadphoneAudioExposure expects the unit to be:
HKUnit.decibelAWeightedSoundPressureLevel()

Proposed Fix:
`case .environmentalAudioExposure,
.headphoneAudioExposure:

        if #available(iOS 13.0, *) {
            return quantity(unit: HKUnit.decibelAWeightedSoundPressureLevel())
        } else {
            throw HealthKitError.notAvailable(
                "\(type) is not available for the current iOS"
            )
        }`

Let me know if you’d like me to submit a PR for this. Thanks!