v21.6

What's Changed

• Add accessibility label to stop bookmark by @ualch9 in #556
• Update app version to 21.6 by @aaronbrethorst in #558
• Adds accessibility to TripStopListItem by @ualch9 in #559
• DRY trip stop accessibility value strings by @ualch9 in #562

Full Changelog: v21.5.1...v21.6