Update to Firebase 12.6.0

[github-actions]

The Firebase Apple SDK (12.6.0) is now available. For more details, see
the Firebase Apple SDK release notes.

To install this SDK, see Add Firebase to your project.

What's Changed

• [Release] Update Unreleased changelog entries by @andrewheard in [Release] Update Unreleased changelog entries firebase/firebase-ios-sdk#15436
• [Firebase AI] Fix Google AI useLimitedUseAppCheckTokens config by @andrewheard in [Firebase AI] Fix Google AI useLimitedUseAppCheckTokens config firebase/firebase-ios-sdk#15423
• [Firebase AI] Add internal JSON Schema support in GenerationConfig by @andrewheard in [Firebase AI] Add internal JSON Schema support in GenerationConfig firebase/firebase-ios-sdk#15404
• Fix typos by @paulb777 in Fix typos firebase/firebase-ios-sdk#15445
• Fix typo in SecureTokenService comment by @gibachan in Fix typo in SecureTokenService comment firebase/firebase-ios-sdk#15448
• [Release] Update Carthage artifacts for 12.5.0 by @andrewheard in [Release] Update Carthage artifacts for 12.5.0 firebase/firebase-ios-sdk#15452
• [Release] Update Carthage README for FirebaseAILogicBinary by @andrewheard in [Release] Update Carthage README for FirebaseAILogicBinary firebase/firebase-ios-sdk#15453
• [Release] Update versions for 12.6.0 by @andrewheard in [Release] Update versions for 12.6.0 firebase/firebase-ios-sdk#15458
• remove func from codebase by @themiswang in remove func from codebase firebase/firebase-ios-sdk#15456
• [AI] Server Prompt Templates by @paulb777 in [AI] Server Prompt Templates firebase/firebase-ios-sdk#15402
• Prevent stale configuration data after iOS device restore by @tusharkhandelwal8 in Prevent stale configuration data after iOS device restore firebase/firebase-ios-sdk#15442

New Contributors

• @gibachan made their first contribution in Fix typo in SecureTokenService comment firebase/firebase-ios-sdk#15448

Full Changelog: firebase/firebase-ios-sdk@12.5.0...12.6.0