[Release] Update unreleased changelog entries to `11.12.0` (#14726)

FirebaseAuth/CHANGELOG.md

@@ -1,4 +1,4 @@
-# Unreleased
+# 11.12.0
 - [fixed] Fix a `fatalError` unenrolling from MFA. An invalid user token now throws an
   `invalidUserToken` error instead of crashing. (#14663)
 - [fixed] Fix the parameter from "languageCode" to "lang" in ActionCodeURL. (#14664)

FirebaseCore/CHANGELOG.md

@@ -1,4 +1,4 @@
-# Unreleased
+# Firebase 11.12.0
 - [changed] Firebase now requires at least Xcode 16.2. See
   https://developer.apple.com/news/?id=9s0rgdy9 for more info.
 

FirebaseFunctions/CHANGELOG.md

@@ -1,4 +1,4 @@
-# Unreleased
+# 11.12.0
 - [fixed] Fix regression from 11.6.0 where `HTTPSCallable` did not invoke
   completion block on main thread (#14653).
 

FirebaseVertexAI/CHANGELOG.md

@@ -1,4 +1,4 @@
-# Unreleased
+# 11.12.0
 - [added] **Public Preview**: Added support for specifying response modalities
   in `GenerationConfig`. This includes **public experimental** support for image
   generation using Gemini 2.0 Flash (`gemini-2.0-flash-exp`). (#14658)

Firestore/CHANGELOG.md

@@ -1,4 +1,4 @@
-# Unreleased
+# 11.12.0
 - [fixed] Fixed the `null` value handling in `isNotEqualTo` and `notIn` filters.
 
 # 11.11.0