Bump minimum supported Swift version

[testableapple]

🔗 Issue Links

Resolve https://github.com/GetStream/ios-issues-tracking/issues/834

🎯 Goal

Get rid of Xcode 14 on CI

☑️ Contributor Checklist

• [x] I have signed the Stream CLA (required)
• [x] This change follows zero ⚠️ policy (required)
• [ ] This change should receive manual QA
• [ ] Changelog is updated with client-facing changes
• [ ] New code is covered by unit tests
• [ ] Comparison screenshots added for visual changes
• [ ] Affected documentation updated (Docusaurus, tutorial, CMS)

🎁 Meme