[Auth] Add CHANGELOG entry for #14067 (#14078)

Author: andrewheard

FirebaseAuth/CHANGELOG.md

@@ -3,6 +3,10 @@
   logged out when upgrading from Firebase 8.10.0 or earlier to Firebase 11.
   Note that this fix will not be in the 11.5.0 zip and Carthage
   distributions, but will be included from 11.6.0 onwards. (#14011)
+- [fixed] Restore Firebase 10 keychain error handling behavior when retrieving
+  Firebase Auth tokens, potentially causing user sign-out on Firebase 11. Note
+  that this fix will not be in the 11.5.0 zip and Carthage distributions, but
+  will be included from 11.6.0 onwards. (#14067)
 
 # 11.4.0
 - [fixed] Restore Firebase 10 behavior by ignoring `nil` display names used