Apple sign-in gated by sign-up mode; native dev indicator

What's Changed

• Fix Expo iOS bump workflow by @mikepitre in https://github.com/clerk/clerk-ios/pull/483
• Update Expo release Slack notification by @mikepitre in https://github.com/clerk/clerk-ios/pull/485
• Gate Apple sign-in transfer by sign-up mode by @seanperez29 in https://github.com/clerk/clerk-ios/pull/487
• Render development mode indicator natively by @prestonwebdev in https://github.com/clerk/clerk-ios/pull/484

New Contributors

• @prestonwebdev made their first contribution in https://github.com/clerk/clerk-ios/pull/484

Full Changelog: https://github.com/clerk/clerk-ios/compare/1.2.5...1.2.6