v17.8.14

What's Changed

• Add AsyncMutex class by @AArnott in #1223
• Add AsyncLazy<T>.Dispose() method by @AArnott in #1218
• Build 17.8 stable version by @AArnott in #1226
• Bump Microsoft.VisualStudio.Validation from 17.6.11 to 17.8.8 by @dependabot in #1230

Full Changelog: v17.7.35...v17.8.14