Update DatadogNet.Core.Mac to 3.15.0.1

[sbokatuk]

sbokatuk/DatadogNet.Mac published v3.15.0.1: DatadogNet.Core.Mac at 3.15.0.1.

• Release: https://github.com/sbokatuk/DatadogNet.Mac/releases/tag/v3.15.0.1
• Release notes: https://github.com/sbokatuk/DatadogNet.Mac/blob/HEAD/docs/release-notes/3.15.0.1.md
• The pin lives in this repository's Directory.Build.props; until it moves, the daily upstream-drift check keeps reporting it behind.